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Site Fidelity (site + fidelity)

Distribution by Scientific Domains
Life Sciences85%
Earth and Environmental Science14%
Distribution within Life Sciences
Ornithology29%
Ecology & Organismal Biology25%

Kinds of Site Fidelity

  • high site fidelity
    		•

    Selected Abstracts

    Site fidelity and the demographic implications of winter movements by a migratory bird, the harlequin duck Histrionicus histrionicus

    JOURNAL OF AVIAN BIOLOGY, Issue 3 2006
    Samuel A. Iverson
    Understanding the degree of demographic connectivity among population segments is increasingly recognized as central to the fields of population ecology and conservation biology. However, delineating discrete population units has proven challenging, particularly for migratory birds as they move through their annual cycle. In this study, radio telemetry was used to assess movement rates among habitats by harlequin ducks Histrionicus histrionicus during the non-breeding season in Prince William Sound, Alaska. A total of 434 females were outfitted with radio transmitters over six years of data collection, and their signals tracked by aircraft. Using a spatially nested design, it was determined that 75% of radioed females remained in the bay or coastline area where they were originally trapped, 94% remained on the same island or mainland region of Prince William Sound where they began the winter period, and 98% remained within the 4500 km2 study area as a whole. Home range analyses corroborated these findings, indicating that the scale of individual movements was small, with 95% kernel home range estimates averaging only 11.5±2.2 km2. A simple demographic model, which incorporated estimates for population size, survival, and movement rates, was used to infer the degree of independence among population segments. Immigrant females were found to contribute little to population numbers in most areas, accounting for only 4% of the adult female population at a scale of approximately 100 km2. These results have important implications for the scale of conservation action for the species and demonstrate that winter movements can have a strong influence local population dynamics. [source]

    Site fidelity and movements of humpback whales (Megaptera novaeangliae) on the Brazilian breeding ground, southwestern Atlantic

    MARINE MAMMAL SCIENCE, Issue 4 2010
    Leonardo L. Wedekin
    Abstract Site fidelity and movements were studied for humpback whales photo-identified from 1989 to 2006 in the Abrolhos Bank, southwestern Atlantic, Brazil. A total of 2,612 individuals were identified, 374 of which were observed on more than one occasion. The cumulative number of identified whales has increased since 1989. Recapture rate was low and varied among different years. A total of 33 whales was observed using the Abrolhos Bank for longer than 10 yr, up to a maximum of 16 yr. Our data suggest that different whales show distinct movement rates. Some whales used a large extent of the Abrolhos Bank region. Opportunistic photo-identification data (on the scale of the Brazilian coast from 4° to 23°S) revealed important information about stock identity. The longest distance between within-season resightings was over 600 km, while one whale was observed in two locations separated by more than 1,400 km in different years. Long-range movements within and between seasons support the single stock hypothesis for humpback whales wintering off the Brazilian coast. [source]

    Effects of tail autotomy on survival, growth and territory occupation in free-ranging juvenile geckos (Oedura lesueurii)

    AUSTRAL ECOLOGY, Issue 4 2006
    JONATHAN K. WEBB
    Abstract Many animals autotomize their tails to facilitate escape from predators. Although tail autotomy can increase the likelihood of surviving a predatory encounter, it may entail subsequent costs, including reduced growth, loss of energy stores, a reduction in reproductive output, loss of social status and a decreased probability of survival during subsequent encounters with predators. To date, few studies have investigated the potential fitness costs of tail autotomy in natural populations. I investigated whether tail loss influenced survival, growth and territory occupation of juvenile velvet geckos Oedura lesueurii in a population where predatory snakes were common. During the 3-year mark,recapture study, 32% of juveniles voluntarily autotomized their tails when first captured. Analysis of survival using the program mark showed that voluntary tail autotomy did not influence the subsequent survival of juvenile geckos. Survival was age-dependent and was higher in 1-year-old animals (0.98) than in hatchlings (0.76), whereas recapture probabilities were time-dependent. Growth rates of tailed and tailless juveniles were very similar, but tailless geckos had slow rates of tail regeneration (0.14 mm day,1). Tail autotomy did not influence rock usage by geckos, and both tailed and tailless juveniles used few rocks as diurnal retreat sites (means of 1.64 and 1.47 rocks, respectively) and spent long time periods (85 and 82 days) under the same rocks. Site fidelity may confer survival advantages to juveniles in populations sympatric with ambush foraging snakes. My results show that two potential fitness costs of tail autotomy , decreased growth rates and a lower probability of survival , did not occur in juveniles from this population. However, compared with juveniles, significantly fewer adult geckos (17%) voluntarily autotomized their tails during capture. Because adults possess large tails that are used for lipid storage, the energetic costs of tail autotomy are likely to be much higher in adult than in juvenile O. lesueurii. [source]

    Philopatry and Homing Behavior of Sea Snakes (Laticauda colubrina) from Two Adjacent Islands in Fiji

    CONSERVATION BIOLOGY, Issue 5 2002
    Sohan Shetty
    Even in highly vagile species, local populations may comprise ecologically separate entities if most animals display strong and consistent site attachment. We conducted a mark-recapture study on yellow-lipped sea kraits ( Laticauda colubrina) on two small Fijian islands separated by 5.3 km. These snakes forage over many kilometers in the ocean, but return to land to reproduce, slough, and digest their food. Recovery of marked snakes showed that the populations on these two islands were essentially separate. Relocated snakes returned "home" almost immediately after they were released. Growth rates and mean adult body sizes of male sea snakes also differed between the two islands. This high site fidelity means that activities such as resort development or commercial harvesting for the skin trade are likely to have intense localized effects rather than diffuse broad-scale effects on sea snake populations. Our results also call into question the feasibility of plans to reintroduce snake populations to areas where a species has been eliminated by overexploitation. Resumen: La escala espacial a la que las perturbaciones antropogénicas afectan a una población de animales depende del grado de filopatría y de la búsqueda del hogar de individuos dentro de esta población. Aún en especies altamente móviles, las poblaciones locales pueden contener entidades ecológicamente separadas si la mayoría de los animales presentan un apego fuerte y consistente por un sitio. Llevamos a cabo un estudio de marcado-recaptura en las serpientes marinas de labios amarillos ( Laticauda colubrina) de dos islas pequeñas de Fiji, separadas por 5.3 km. Estas serpientes forrajean a lo largo de muchos kilómetros en el océano, pero regresan a tierra a reproducirse, mudar de piel y digerir su comida. La recuperación de serpientes mostró que las poblaciones en estas dos islas estaban substancialmente separadas. Las serpientes reubicadas regresaron a "casa" casi inmediatamente después de haber sido liberadas. Las tasas de crecimiento y el tamaño promedio de machos también difirieron entre las dos islas. Esta alta fidelidad al sitio significa que las actividades tales como el desarrollo de un centro turístico o de la cosecha comercial para el comercio de la piel son probablemente factores que tendrán efectos localizados en lugar de efectos difusos de amplia escala sobre las poblaciones de serpientes marinas. Nuestros resultados también cuestionan la viabilidad de planes para reintroducir poblaciones de serpientes en áreas donde una especie ha sido eliminada por sobreexplotación. [source]

    Factors Affecting Population Assessments of Desert Tortoises

    CONSERVATION BIOLOGY, Issue 5 2000
    Jerome E. Freilich
    With a wide geographic range and more living individuals than any other listed land animal, biologists have needed to detect population trends against a "noisy" background of strong annual changes. We obtained annual population estimates of desert tortoises over 6 consecutive years at a 2.59-km2 plot in Joshua Tree National Park, California. Our estimates, based on weekly spring surveys, varied substantially, particularly between wet and dry years. Concurrently, we followed 10 radiotagged animals for 3 years to corroborate the surveys. Population density was determined separately for each year and for all years combined. Our best population estimate was an average of 67 adult tortoises, three times more than the density reported in a 1978 survey of the same site. Annual mortality was low ( <10%), and the animals showed extreme site fidelity. Apparent changes in population size were most strongly related to the animals' varying susceptibility to capture. In dry years, home ranges decreased, captures decreased, and effort required to find each tortoise nearly doubled. Our data confirm that tortoises are likely to be undercounted during dry years and call into question earlier studies conducted during droughts. Resumen: Las tortugas del desierto han sido tema de controversia desde que fueron enlistadas como amenazadas en 1990. Con un amplio rango de distribución geográfica y más individuos vivos que cualquier otro animal terrestre enlistado, los biólogos han necesitado detectar tendencias poblacionales contra un trasfondo "ruidoso" de cambios anuales fuertes. Obtuvimos estimaciones de la población anual de tortugas del desierto por seis años consecutivos en un cuadrante de 2.59 Km2 en el Parque Nacional Joshua Tree de California. Nuestras estimaciones, basadas en sondeos semanales de primavera, variaron sustancialmente, particularmente al comparar años lluviosos con años secos. Al mismo tiempo, monitoreamos por tres años a 10 animales marcados con radiotransmisores para corroborar los sondeos. La densidad poblacional estuvo determinada por separado para cada año y para todos los años combinados. Nuestras mejores estimaciones de densidad poblacional fueron en promedio de 67 adultos, tres veces más que la densidad reportada en un sondeo de 1978 en el mismo sitio. La mortalidad anual fue baja ( <10%) y los animales mostraron una fidelidad extrema por el sitio. Los cambios aparentes en el tamaño poblacional estuvieron más fuertemente relacionados con la variación en la susceptibilidad de captura de los animales. En años secos, el rango de hogar disminuyó, las capturas disminuyeron, y el esfuerzo requerido para encontrar cada tortuga fue de casi el doble. Nuestros datos confirman que las tortugas son probablemente mal contadas ( menos) durante los años de seca y ponen en duda estudios previos realizados durante secas. [source]

    Sex, isolation and fidelity: unbiased long-distance dispersal in a terrestrial amphibian

    ECOGRAPHY, Issue 5 2006
    M. Alex Smith
    Amphibians in general are considered poor dispersers and thus their dispersal curve should be dominated by short movements. Additionally, as male toads do not compete for females and sexual selection is by female choice, dispersal should be male-biased. Furthermore, since adults are site-loyal and polygynous, juveniles should move farther and faster than adults. We tested the hypotheses that dispersal would be limited and both sex- and age-biased in a population of Fowler's toads Bufo fowleri at Lake Erie, Ontario, Canada. Based on a mark-recapture study of 2816 toads, 1326 recaptured at least once, we found that although the toads did show high site fidelity, the dispersal curve was highly skewed with a significant "tail" where the maximum distance moved by an adult was 34 km. Dispersal was neither sex-biased nor age-biased despite clear theoretical predictions that dispersal should be biased towards males and juveniles. We conclude that the resource competition hypothesis of sex-biased dispersal does not predict dispersal tendencies as readily for amphibians as for mammals and birds. Toad dispersal only appears to be juvenile-biased because the juveniles are more abundant than the adults, not because they are the more active dispersers. [source]

    Variation in the relationship between numbers of breeding pairs and woodland area for passerines in fragmented habitat

    ECOGRAPHY, Issue 1 2000
    P. E. Bellamy
    Species may differ in the relationship between the numbers of breeding pairs present and woodland area, because the proportion of a wood that forms suitable habitat will vary with woodland size. In this paper, we examine the pattern of variation in abundance with woodland area for eight breeding bird species, and also show how this pattern varied between years. During 1990-1997, we made annual censuses of 53,160 woods, of up to 10 ha in size, and fitted a power function to describe the relationships between numbers of breeding pairs and woodland area. Seven of the eight species, blackbird Turdus merula, dunnock Prunella modularis, wren Troglodytes troglodytes, great tit Parus major, chaffinch Fringilla coelebs, robin Erithacus rubecula and blue tit Parus caeruleus showed a pattern of proportionally higher numbers in smaller woods. Only long-tailed tit Aegithalos caudatus occurred in proportionally higher numbers in larger woods. Blackbird and dunnock showed a trend towards lower numbers in large woods during years with low regional population levels; for these species large woods may provide sub-optimal habitat. Great tit, blue tit, chaffinch and robin showed the opposite trend, towards lower numbers in small woods during years with low regional population levels; for these species small woods may provide sub-optimal habitat. Wren and long-tailed tit, which also showed large annual population fluctuations, showed no change in distribution with regional population level. In great tit and chaffinch, the distribution of pairs in any one year may have been influenced by site fidelity producing a lag in the response associated with regional population levels. [source]

    Movements of Murray cod (Maccullochella peelii peelii) in a large Australian lowland river

    ECOLOGY OF FRESHWATER FISH, Issue 4 2009
    J. D. Koehn
    Abstract,,, This study of Murray cod (Maccullochella peelii peelii) movements in a large lowland river in south-eastern Australia indicated that the species was not sedentary, but undertook complex movements that followed a seasonal pattern. While there were sedentary periods with limited home ranges and high site fidelity, Murray cod also under took larger movements for considerable portions of the year coinciding with its spawning schedule. This generally comprised movements (up to 130 km) from a home location in late winter and early spring to a new upstream position, followed by a rapid downstream migration typically back to the same river reach. Timing of movements was not synchronous amongst individuals and variation in the scale of movements was observed between individuals, fish size, original location and years. [source]

    Lateral movement of common carp (Cyprinus carpio L.) in a large lowland river and floodplain

    ECOLOGY OF FRESHWATER FISH, Issue 1 2009
    M. J. Jones
    Abstract,,, Common carp (Cyprinus carpio L.) are a major freshwater invader and knowledge of their movements is important for planning control efforts. To investigate the movement patterns of common carp, radio-tags were implanted into 46 adult fish; 37 near a large floodplain wetland, the Barmah-Millewa forest, and 9 in the Murray River approximately 175 km upstream. Tagged fish were located every second week between August 1999 and March 2001. Common carp occupied total linear ranges (TLR) between 0.4 and 238 km (mean 30 ± 61 km), with 25 fish (62.5%) occupying a TLR < 10 km. Two fish made large distance movements approximately 650 km downstream. Fish sex, the number of locations, time at large, or tagging location explained little variability (P > 0.05) in TLR. Monthly distance from release varied from 0.04 to 238 km (mean 15 ± 44 km), and was not significantly related to river discharge and water temperature, but 29 of 31 (93.5%) fish tagged at Barmah moved from the Murray River into adjacent floodplain habitats upon flooding. Five fish (12.5%) moved large distances (>127 km) upstream of the Barmah-Millewa forest. Fourteen fish (35%) showed site fidelity to within 20 m and usually occupied one or two home sites. Twenty-six fish (65%) showed site fidelity to within 100 m occupying up to five sites during the study period. Movement patterns of common carp were complex, and individuals exhibited different strategies, which is typical of invasive species. Efforts to control and potentially reduce common carp populations in regulated river-floodplain environments should target key floodplain access points and over-wintering habitats to reduce adult biomass, spawning and recruitment levels. [source]

    Movements and habitat use of common carp (Cyprinus carpio) and Murray cod (Maccullochella peelii peelii) juveniles in a large lowland Australian river

    ECOLOGY OF FRESHWATER FISH, Issue 2 2007
    M. J. Jones
    Abstract,,, Native Murray cod (Maccullochella peelii peelii) are listed as a nationally vulnerable species, whereas non-native common carp (Cyprinus carpio) are widespread and abundant. Understanding key aspects of life history, such as movement patterns and habitat selection by juvenile Murray cod and common carp, might be useful for conserving Murray cod populations and controlling common carp numbers. We used radio-telemetry to track eight juvenile Murray cod and seven juvenile common carp in the Murray River, Australia, between March and July 2001. Common carp occupied a significantly greater total linear range (mean ± SD: 1721 ± 1118 m) than Murray cod (mean ± SD: 318 ± 345 m) and the average daily movement was significantly greater for common carp (mean ± SD: 147 ± 238 m) than for Murray cod (mean ± SD: 15 ± 55 m). All Murray cod and five of the seven common carp displayed site fidelity or residency to one, two or three locations. Murray cod were found only in the mainstream Murray River among submerged woody habitats, whereas common carp occurred equally in mainstream and offstream areas, and among submerged wood and aquatic vegetation. Murray cod were found in deeper (mean ± SD: 2.3 ± 0.78 m) and faster waters (mean ± SD: 0.56 ± 0.25 m·s,1) compared with common carp (mean ± SD: 1 ± 0.54 m; 0.08 ± 0.09 m·s,1) respectively. The presence of juvenile Murray cod only amongst submerged wood is an indication that these habitats are important and should be preserved. Conversely, juvenile common carp were equally present among all habitats sampled, suggesting that habitat selection is less specific, possibly contributing to their widespread success. [source]

    Factors affecting habitat selection by a small spawning charr population, bull trout, Salvelinus confluentus: implications for recovery of an endangered species

    FISHERIES MANAGEMENT & ECOLOGY, Issue 1 2004
    R. C. Wissmar
    Abstract Bull trout, Salvelinus confluentus (Suckley), populations are declining in many streams of North America and are listed under the Endangered Species Act in the United States. Many small populations are isolated in fragmented habitats where spawning conditions and success are not well understood. Factors affecting habitats selected for redds by spawning bull trout and redd habitat characteristics within Gold Creek, a headwater stream in the Yakima River within the Columbia River basin, Washington State, USA, were evaluated. Most spawning (>80% of the redds) occurred in upstream habitats after dewatering of downstream channels isolated fish. Habitats were selected or avoided in proportions different to their availability. For example, most bull trout selected pools and glides and avoided riffles despite the latter being more readily available. Although preferences suggest influences of prolonged fish entrapment, site fidelity could be important. A habitat with redds commonly contained abundant cover, gravel substratum and higher stream flows. The major factors influencing habitat selection by spawning fish and their persistence in streams of the Yakima and Columbia River regions include entrapment of fish by dewatering of channels and geographical isolation by dams. The goal of the US Government's recovery plan is ,to ensure the long-term persistence of self-sustaining bull trout populations'. Recovery plans linked to provisions for protecting and conserving bull trout populations and their habitats were recommended. Landscape approaches are needed that provide networks of refuge habitats and greater connectivity between populations. Concurrent recovery efforts are encouraged to focus on protecting small populations and minimizing dangers of hybridization. [source]

    Resident and transient dynamics, site fidelity and survival in wintering Blackcaps Sylvia atricapilla: evidence from capture,recapture analyses

    IBIS, Issue 2 2007
    EDUARDO J. BELDA
    In their winter quarters, migrant birds may either remain within a small area (resident strategy) or move frequently over a large area looking for locally abundant food (transient strategy). It has been suggested that both strategies could simultaneously occur in the same population. We used time-since-marking capture,recapture models to infer the coexistence of these two behavioural strategies (transient and resident) among wintering Blackcaps Sylvia atricapilla using weekly recapture data over a 7-year period. A related question is whether Blackcaps, if surviving to the next winter, always return to the same wintering area, so we also used this approach to analyse winter site fidelity and to estimate annual survival probabilities. Model selection supported the existence of heterogeneity in survival estimates for both the within-season and the interannual survival probabilities, i.e. there was evidence for the existence of transients. It was estimated that 26% of the Blackcaps were resident during the winter. Mean apparent annual survival probability was 0.46 (se = ±0.11). However, there was some evidence suggesting that not all individuals showed winter site fidelity. The estimated proportion of individuals that, if alive, returned to the wintering area was 28%. This is the first study to show the existence of these two behavioural strategies (residence and transience) among wintering Blackcaps, and the first confirming this pattern using capture,recapture models. These models considering transient and resident dynamics may become an important tool with which to analyse wintering strategies. [source]

    Pair bond and breeding success in Blue Tits Parus caeruleus and Great Tits Parus major

    IBIS, Issue 1 2005
    MIRIAM PAMPUS
    Data from 939 nests of the Blue Tit Parus caeruleus and 1008 nests of the Great Tit P. major from nestboxes provided in superabundance in mixed forest study sites between 1976 and 2001 were analysed to examine the effects of mate retention on breeding success and the relationship between mate fidelity and site fidelity. Most birds retained their former partner (76% in Great Tits and 65% in Blue Tits). The probability of a pair divorcing was affected by male age in Great Tits, divorce being more likely in pairs with first-year males. Great Tit pairs breeding together for a second season bred earlier, but had no higher breeding success than pairs breeding together for the first time. In Blue Tits laying date and start of incubation tended to be earlier in pairs breeding together for a second season, but hatching and fledging dates were not earlier than in other pairs. Great Tit pairs breeding together for two consecutive seasons bred earlier in the second season than in the first, but breeding success did not differ significantly between years. In both species, breeding performance did not differ between pairs that divorced after a season and pairs that stayed together. Thus breeding success did not determine whether a pair divorced or bred together again. Neither Blue Tits nor Great Tits improved their breeding performance through divorce. Blue Tit females even had fewer fledglings in the year after divorce than in the year before. Mate retention affected breeding site fidelity. Blue Tit females had greater breeding dispersal distances between consecutive years when re-mating than when breeding again with the same mate. In Great Tits both males and females dispersed more when re-mating than when retaining the former partner, suggesting that mate retention increased the chance of retaining the breeding site. In both species, breeding dispersal distances did not differ between pairs that divorced and pairs in which one mate disappeared. Because no major advantage of mate retention was evident, we suggest that mate retention evolved under different conditions than those found in study sites with high breeding densities and a superabundance of artificial nesting sites. [source]

    Population dynamics and reproduction of Northern Lapwings Vanellus vanellus in a meadow restoration area in central Sweden

    IBIS, Issue 3 2002
    Åke Berg
    To investigate the effectiveness of a meadow restoration programme, we studied the relationships between population changes and environmental changes, return rates and hatching success in a population of Northern Lapwings Vanellus vanellus. The study was performed on mixed farmland (59 km2) in central Sweden, an area that underwent extensive meadow restoration between 1985 and 1994. The study included more than 2600 nests, supplemented with observations of 127 individually colour-ringed Northern Lapwings. The breeding population varied (2.7,5.3 pairs/km2), but showed no significant trend with time. The population increased in years with high spring flooding levels. Population size was unrelated to demographic factors (e.g. hatching success the previous year (14,50%), and return rate). Lapwings moved considerably between years and their nest site fidelity was unrelated to previous hatching success or other factors, suggesting that changes in habitat quality and migration between populations were important in regulating population size. Recent extensive meadow restoration did not seem to aid the Northern Lapwing population; birds continued nesting on tillage even though most nests were destroyed by farming activities. A relatively high relaying frequency improved hatching success, which was still lowest in the most preferred habitats (spring sown crops, total hatching success c. 30%). The few Northern Lapwings breeding in the least preferred habitats (meadows and cultivated grassland) had a better hatching success (> 70% total hatching success), suggesting that habitat selection was not determined by hatching success. From these results, recommendations are made for the management of Northern Lapwing (and associated species) populations on farmland. [source]

    Local annual survival of booming male Great Bittern Botaurus stellaris in Britain, in the period 1990,1999

    IBIS, Issue 1 2002
    Gillian Gilbert
    Male Great Bitterns Botaurus stellaris have individually distinctive boom vocalizations which have been used since 1990 to count the British population accurately. We used vocal individuality to identify birds between years and analyse the survival of the British booming population. We used six instances of Great Bitterns known to be the same birds (from radio tracking and re-sighting of darvic rings) in successive years to provide a means of identification independent from vocalizations. All of these birds remained in the same territory from one year to the next. Seven spectrogram measures were chosen as quantitative descriptors of Great Bittern booms. Boom similarity was expressed in terms of Euclidean ,acoustic' distance between descriptors of pairs of birds. Great Bitterns that were known to be the same birds had more similar booms across years than those known to be different. The acoustic distances and knowledge of site fidelity were used to construct parsimonious rules on which to base re-identification decisions and to build survival histories. Great Bittern local survival in Britain as a whole was estimated as 70% (± 5.1 se) with survival in north-west England (at Leighton Moss) higher (82.8%, ± 7.3 se) than that in East Anglian sites (65.2%, ± 5.4 se) (,12 = 3.4, P = 0.07). Movements of males between years were apparent between sites within the Suffolk and Norfolk coastal regions but not on a large scale. Survival of adult males in East Anglia was positively related to winter rainfall, but there was no significant relationship with winter temperature. There was a positive relationship between the annual population change in East Anglia and the annual local adult survival rate. [source]

    Multiscale patterns of movement in fragmented landscapes and consequences on demography of the snail kite in Florida

    JOURNAL OF ANIMAL ECOLOGY, Issue 2 2006
    JULIEN MARTIN
    Summary 1Habitat loss and fragmentation are major factors affecting vertebrate populations. A major effect of these habitat alterations is that they reduce movement of organisms. Despite the accepted importance of movement in driving the dynamics of many natural populations, movement of vertebrates in fragmented landscapes have seldom been estimated with robust statistical methods. 2We estimated movement probabilities of snail kites Rosthramus sociabilis within the remaining wetlands in Florida. Using both radio-telemetry and banding information, we used a multistate modelling approach to estimate transition probabilities at two temporal scales (month; year) and multiple spatial scales. We examined kite movement among wetlands altered by three different levels of fragmentation: among wetlands separated by small physical barriers (e.g. road); among wetlands separated by moderate amount of matrix (< 5 km); and among wetlands separated by extensive matrix areas (> 15 km). 3Kites moved extensively among contiguous wetlands (movement probability 0·29 per month), but significantly less among isolated wetlands (movement probability 0·10 per month). 4Kites showed high levels of annual site fidelity to most isolated wetlands (probability ranged from 0·72 to 0·95 per year). 5We tested the effects of patch size and interpatch distance on movement. Our modelling indicated an effect of both distance and patch size on juveniles' movement (but not adult) when examining movements among fragments. 6Only a small proportion of kites escaped a regional drought by moving to refugia (wetlands less affected by drought). Many individuals died after the drought. During drought adult survival dropped by 16% while juvenile survival dropped by 86% (possibly because juveniles were less likely to reach refugia). 7We hypothesize that fragmentation may decrease kite's resistance to drought by restricting exploratory behaviour. [source]

    Effects of age, breeding experience, mate fidelity and site fidelity on breeding performance in a declining population of Cassin's auklets

    JOURNAL OF ANIMAL ECOLOGY, Issue 6 2001
    Peter Pyle
    Summary 1We examined how mate and site fidelity varied with age, experience and sex, and how age, breeding experience, mate experience, site experience and sex affected annual reproductive success and lifetime reproductive output in a declining population of Cassin's auklets (Ptychoramphusaleuticus). Our 276 study birds were 2,14 years of age, recruited at age 2,12 years, and had 0,11 years' breeding experience, 0,8 years' experience with the same mate and 0,11 years' experience in the same nest box. 2Mate fidelity was significantly greater with increasing age in males but not females. There was also a significant negative relationship between mate fidelity and breeding density (as measured by proportion of box occupancy); i.e. the lower the breeding density the higher the incidence of breeding with the same mate. 3Site fidelity showed significant linear and curvilinear increases with age that were significant in females but not males. There was also a significant negative relationship between site fidelity and breeding density; i.e. the lower the breeding density the higher the incidence of breeding at the same site. 4Previous breeding experience had no effect on either mate fidelity or site fidelity, and both mate and site fidelity were significantly lower after a breeding season was skipped. In addition, mate fidelity was significantly lower when a site was switched and vice versa. 5Lifetime reproductive output increased significantly with mate fidelity but showed no relationship with site fidelity. This suggests that fitness is optimized more through mate selection than site selection and that mate fidelity is not a by-product of site fidelity. 6Annual reproductive success showed a significant linear increase with age in males but not females, and a strong parabolic relationship with breeding experience that was significant in both sexes and significantly greater in males than females. 7These results suggest that (i) males may be more responsible for mate selection and females for site selection; (ii) improved foraging experience with age and a cost of reproduction may be more important factors in males than females; and (iii) reproductive success may be optimized by behaviour of the male rather than the female. 8Controlling for the age and experience terms of both parents, experience with a mate had a significant positive linear effect on annual reproductive success. This suggests that mate fidelity is adaptive in Cassin's auklets, and that studies examining the effects of age and experience on reproductive performance should separately consider the duration of the pair bond. 9,Controlling for all other variables, neither experience at a breeding site nor breeding density showed significant correlations with reproductive success. 10,We suggest that reductions in food supply, which correlate with reduced breeding densities, may prevent all but the highest quality breeders (those which have already established a pair bond) from reproducing, and that the increase in quality offsets the reduction in food availability. [source]

    Population structure in the South American tern Sterna hirundinacea in the South Atlantic: two populations with distinct breeding phenologies

    JOURNAL OF AVIAN BIOLOGY, Issue 4 2010
    Patrícia J. Faria
    The South American tern Sterna hirundinacea is a migratory species for which dispersal, site fidelity and migratory routes are largely unknown. Here, we used five microsatellite loci and 799,bp partial mitochondrial DNA sequences (Cytochrome b and ND2) to investigate the genetic structure of South American terns from the South Atlantic Ocean (Brazilian and Patagonian colonies). Brazilian and Patagonian colonies have two distinct breeding phenologies (austral winter and austral summer, respectively) and are under the influence of different oceanographic features (e.g. Brazil and Falklands/Malvinas ocean currents, respectively), that may promote genetic isolation between populations. Results show that the Atlantic populations are not completely panmictic, nevertheless, contrary to our expectations, low levels of genetic structure were detected between Brazilian and Patagonian colonies. Such low differentiation (despite temporal isolation of the colonies) could be explained by demographic history of these populations coupled with ongoing levels of gene flow. Interestingly, estimations of gene flow through Maximum likelihood and Bayesian approaches has indicated asymmetrical long term and contemporary gene flow from Brazilian to Patagonian colonies, approaching a source,sink metapopulation dynamic. Genetic analysis of other South American tern populations (especially those from the Pacific coast and Falklands,Malvinas Islands) and other seabird species showing similar geographical distribution (e.g. royal tern Thalasseus maximus), are fundamental in gaining a better understanding of the main processes involved in the diversification of seabirds in the southern hemisphere. [source]

    Egg-yolk androgen and carotenoid deposition as a function of maternal social environment in barn swallows Hirundo rustica

    JOURNAL OF AVIAN BIOLOGY, Issue 4 2010
    Rebecca J. Safran
    Evidence is mounting that female animals use egg-yolk compounds (e.g. steroids, antioxidants) to adaptively engineer the quality of their offspring as a function of several maternal and environmental factors. Though adjustments to yolk allocation have been well-characterized as a function of parental phenotypes, we know very little about how an individual's social environment influences yolk composition. Here, we consider how two types of yolk compounds, androgens and carotenoids, relate to the maternal social environment during the egg-laying period, controlling statistically for known correlations between various aspects of parental quality and egg yolk compounds. Barn swallows Hirundo rustica erythrogaster breed in groups of highly variable size and spacing, allowing us to test whether or not the social environment is correlated with these maternal effects. We found no relationship between carotenoid levels in eggs as a function of colony size, colony density, or nearest-neighbor distance. However, eggs from females in larger groups had lower concentrations and total amounts of yolk androgens than those from females in smaller, less dense social settings. Our results counter previous predictions and literature, showing that females breeding in large groups deposit more androgen in eggs, mechanistically, because they compete more with conspecifics and have higher circulating androgen levels themselves and, functionally, because it could be advantageous for their offspring to show high androgen-mediated competitive abilities early in life. Instead, because group size in this species is governed largely by site fidelity and the availability of old nests for re-use, and because reproductive output does not differ as a function of group size, it may be that competition is greater for limited nests in small groups, thus elevating androgen levels. Further, yolk androgens were previously shown to be affected by male quality, and the greater concentrations and amounts of yolk androgens in smaller sites may reflect differential allocation to darker males found at these sites. [source]

    Density-dependent growth rate in an age-structured population: a field study on stream-dwelling brown trout Salmo trutta

    JOURNAL OF FISH BIOLOGY, Issue 10 2009
    R. Kaspersson
    A field experiment during autumn, winter and spring was performed in a small stream on the west coast of Sweden, aiming to examine the direct and indirect consequences of density-dependent intercohort competition in brown trout Salmo trutta. Individual growth rate, recapture rate and site fidelity were used as response variables in the young-of-the-year (YOY) age class, experiencing two different treatments: presence or absence of yearlings and over-yearlings (age , 1+ year individuals). YOY individuals in stream sections with reduced density of age , 1+ year individuals grew significantly faster than individuals experiencing natural cohort structure. In the latter, growth rate was negatively correlated with density and biomass of age , 1+ year individuals, which may induce indirect effects on year-class strength through, for example, reduced fecundity and survival. Movement of YOY individuals and turnover rate (i.e. proportion of untagged individuals) were used to demonstrate potential effects of intercohort competition on site fidelity. While YOY movement was remarkably restricted (83% recaptured within 50 m from the release points), turnover rate was higher in sections with reduced density of age ,1+ year individuals, suggesting that reduced density of age ,1+ year individuals may have released favourable microhabitats. [source]

    Movement patterns of the round stingray Urobatis halleri(Cooper) near a thermal outfall

    JOURNAL OF FISH BIOLOGY, Issue 6 2006
    J. J. Vaudo
    Fine-scale movements and site fidelity of round stingrays Urobatis halleri at Seal Beach California, U.S.A., were examined using acoustic telemetry. Actively tracked fish generally exhibited limited nearshore movement, with greater distances travelled at night when the tide was ebbing than during the day with ebbing tides. Increases in round stingray activity were associated with increases in ambient temperature. Passively tracked fish showed seasonal patterns in their presence at Seal Beach. Males left Seal Beach during the autumn, returned the following spring, and remained in the area until the following autumn. Females spent far less time at Seal Beach, remaining in the area for a few weeks during June and July. Passively tracked round stingrays were recorded more often in the warm waters of the San Gabriel River mouth (the location of a thermal outfall from an electric-generating station) than adjacent beaches, with fish often returning to Seal Beach after periods of absence. Anthropogenic effects resulting from coastal development may have created environmental conditions (i.e. warmer water and finer sediments) that influence the movements and site fidelity of round stingrays. [source]

    Alongshore dispersal and site fidelity of juvenile plaice from tagging and transplants

    JOURNAL OF FISH BIOLOGY, Issue 3 2004
    M. T. Burrows
    Juvenile plaice Pleuronectes platessa(n = 1281) were tagged and released at two locations 300 m apart on a 1 km long sandy beach. Most (>90%) of the fish were recaptured within 100 m of the release site (shown by the colour of the tag), with very few caught >200 m distance after 6 weeks. The changing spatial distribution of marked fish was adequately reproduced by a simple dispersal model with a single parameter: a 78% probability of remaining in a 100 m wide zone from one day to the next, with a 22% chance that fish move into an adjacent zone. In a subsequent similar study at the same beach, fish were either released at the point of capture (n = 881) or transplanted to the alternate site (n = 910) 100 m distant. After 6 weeks, transplanted fish moved along the shore towards their sites of original capture. Fish replaced at the point of capture showed no such movement along the shore. Further modification of the dispersal model to allow for a distinction between dispersal from home sites and from sites away from the original point of collection, was sufficient to reproduce the behaviour of the populations of both transplanted and control treatment groups. The likelihood of dispersal from home sites was much less than that seen at sites away from home. Juvenile plaice thus have a degree of long-shore site fidelity not expected of a fish with strong depth-related migration behaviour in a relatively homogenous habitat. [source]

    Conservation of the Eurasian beaver Castor fiber: an olfactory perspective

    MAMMAL REVIEW, Issue 4 2010
    Róisín CAMPBELL-PALMER
    ABSTRACT 1Chemical communication in mammals includes an array of specific behaviours that are often ignored in terms of their potential relevance to conservation. Often used during territorial or social interactions between animals, chemical communication can also be used as a tool in reintroduction programmes. Reintroductions still exhibit high failure rates and methods to improve success should be investigated. The Eurasian beaver Castor fiber has been widely reintroduced across Europe after its near extinction in the 19th century. 2Using olfactory studies in the beaver, we aim to demonstrate how scent transfers a range of information about the sender which can be used to monitor social and territorial behaviour along with general well-being. Scent manipulation can be used to reduce human,beaver conflicts, and aid reintroduction success through reducing stress and territorial conflicts, and by influencing dispersal and settlement. 3Two species of beavers, the Eurasian beaver and the North American beaver Castor canadensis, occupy freshwater habitats throughout North America and in parts of South America, most of Europe and parts of Asia. Most of the reviewed literature concerns the wild Eurasian beaver, its chemical communication and conservation; however, captive studies and those addressing North American beavers are also included. 4Chemical communication is advanced and has been well documented in this highly territorial species. However, few studies directly link olfaction with conservation practices. 5Olfactory studies in beavers can provide non-invasive methods to monitor translocated animals and indicators of health. We conclude that chemical analysis, olfactory studies and behavioural manipulations involving semiochemicals have important impacts on conservation and can generate practical solutions to conservation problems including aiding animal capture, captive stress reduction, breeding pair formation and release site fidelity. [source]

    THE SOCIAL STRUCTURE OF BOTTLENOSE DOLPHINS, TURSIOPS TRUNCATUS, IN THE BAHAMAS

    MARINE MAMMAL SCIENCE, Issue 4 2004
    Cindy A. Rogers
    Abstract The social structure of coastal ecotype bottlenose dolphins, Tursiops truncatus, is largely unknown as they inhabit regions far from shore. This study reports on a community of bottlenose dolphins , 27 km from Grand Bahama Island (May-September, 1993,2002). Resident and non-resident dolphins occurred in the area. Some dolphins traveled over 320 km between communities; others showed long- term site fidelity up to 17 yr. Average group size was 3,5, and was significantly larger with calves present and significantly smaller when traveling. The half-weight index was used to determine coefficients of association (COA) for individuals of known sex annually and for pooled years. Permutation tests revealed non-random associations and presence of preferred/avoided companions in all data sets. Annual COAs were low: female-female ,= 0.31, male-male ,= 0.30, and mixed-sex ,= 0.26. Mother-calf associations showed the highest values. Some males formed strong, long-term bonds. Female COAs fluctuated with reproductive status. Using pooled data, COAs were lower and the same basic trends were evident. However, strong associations seen in the annual data were not evident in pooled data. Bottlenose dolphins that inhabit offshore, shallow water show many of the same social structure characteristics as in well-studied coastal populations. [source]

    Fine-scale spatial genetic structure and dispersal among spotted salamander (Ambystoma maculatum) breeding populations

    MOLECULAR ECOLOGY, Issue 2 2007
    KELLY R. ZAMUDIO
    Abstract We examined fine-scale genetic variation among breeding aggregations of the spotted salamander (Ambystoma maculatum) to quantify dispersal, interpopulation connectivity and population genetic structure. Spotted salamanders rely on temporary ponds or wetlands for aggregate breeding. Adequate breeding sites are relatively isolated from one another and field studies suggest considerable adult site fidelity; therefore, we expected to find population structure and differentiation at small spatial scales. We used microsatellites to estimate population structure and dispersal among 29 breeding aggregations in Tompkins County, New York, USA, an area encompassing 1272 km2. Bayesian and frequency-based analyses revealed fine-scale genetic structure with two genetically defined demes: the North deme included seven breeding ponds, and the South deme included 13 ponds. Nine ponds showed evidence of admixture between these two genetic pools. Bayesian assignment tests for detection of interpopulation dispersal indicate that immigration among ponds is common within demes, and that certain populations serve as sources of immigrants to neighbouring ponds. Likewise, spatial genetic correlation analyses showed that populations , 4.8 km distant from each other show significant genetic correlation that is not evident at higher scales. Within-population levels of relatedness are consistently larger than expected if mating were completely random across ponds, and in the case of a few ponds, within-population processes such as inbreeding or reproductive skew contribute significantly to differentiation from neighbouring ponds. Our data underscore the importance of these within-population processes as a source of genetic diversity across the landscape, despite considerable population connectivity. Our data further suggest that spotted salamander breeding groups behave as metapopulations, with population clusters as functional units, but sufficient migration among demes to allow for potential rescue and recolonization. Amphibian habitats are becoming increasingly fragmented and a clear understanding of dispersal and patterns of population connectivity for taxa with different ecologies and life histories is crucial for their conservation. [source]

    Genetic structure among closely spaced leks in a peripheral population of lesser prairie-chickens

    MOLECULAR ECOLOGY, Issue 2 2004
    Juan L. Bouzat
    Abstract We evaluated the genetic structure of birds from four closely spaced leks in a peripheral population of lesser prairie-chickens (Tympanuchus pallidicinctus). Analyses of molecular variance revealed significant genetic structuring among birds from different leks for six microsatellite loci (FST = 0.036; P = 0.002), but we found no genetic differentiation at the mtDNA control region. Significant deviations from Hardy,Weinberg revealed an excess of homozygote genotypes within each of the leks studied (FIS = 0.190,0.307), indicative of increased inbreeding. Estimates of relatedness using microsatellite data suggest that the genetic structuring among lesser prairie-chicken leks occurs in part because of a lek mating system in which males at some leks are related. Structuring may also be caused by stochastic effects associated with a historical decline in population size leading to small, semi-isolated leks and high site fidelity by reproductive males. Results from this study suggest that microspatial genetic structuring may occur in lek-mating bird species with low levels of dispersal. [source]

    Movement patterns and study area boundaries: influences on survival estimation in capture,mark,recapture studies

    OIKOS, Issue 8 2008
    Gregg E. Horton
    The inability to account for the availability of individuals in the study area during capture,mark,recapture (CMR) studies and the resultant confounding of parameter estimates can make correct interpretation of CMR model parameter estimates difficult. Although important advances based on the Cormack,Jolly,Seber (CJS) model have resulted in estimators of true survival that work by unconfounding either death or recapture probability from availability for capture in the study area, these methods rely on the researcher's ability to select a method that is correctly matched to emigration patterns in the population. If incorrect assumptions regarding site fidelity (non-movement) are made, it may be difficult or impossible as well as costly to change the study design once the incorrect assumption is discovered. Subtleties in characteristics of movement (e.g. life history-dependent emigration, nomads vs territory holders) can lead to mixtures in the probability of being available for capture among members of the same population. The result of these mixtures may be only a partial unconfounding of emigration from other CMR model parameters. Biologically-based differences in individual movement can combine with constraints on study design to further complicate the problem. Because of the intricacies of movement and its interaction with other parameters in CMR models, quantification of and solutions to these problems are needed. Based on our work with stream-dwelling populations of Atlantic salmon Salmo salar, we used a simulation approach to evaluate existing CMR models under various mixtures of movement probabilities. The Barker joint data model provided unbiased estimates of true survival under all conditions tested. The CJS and robust design models provided similarly unbiased estimates of true survival but only when emigration information could be incorporated directly into individual encounter histories. For the robust design model, Markovian emigration (future availability for capture depends on an individual's current location) was a difficult emigration pattern to detect unless survival and especially recapture probability were high. Additionally, when local movement was high relative to study area boundaries and movement became more diffuse (e.g. a random walk), local movement and permanent emigration were difficult to distinguish and had consequences for correctly interpreting the survival parameter being estimated (apparent survival vs true survival). [source]

    Harbour seal movements and haul-out patterns: implications for monitoring and management

    AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2009
    Louise Cunningham
    Abstract 1.Compliance with conservation legislation requires knowledge on the behaviour, abundance and distribution of protected species. Seal life history is characterized by a combination of marine foraging and a requirement to haul out on a solid substrate for reproduction and moulting. Thus understanding the use of haul out sites, where seals are counted, as well as their at-sea movements is crucial for designing effective monitoring and management plans. 2.This study used satellite transmitters deployed on 24 harbour seals in western Scotland to examine movements and haul-out patterns. 3.The proportion of time harbour seals spent hauled out (daily means of between 11 and 27%) varied spatially, temporally and according to sex. The mean haul-out duration was 5,h, with a maximum of over 24,h. 4.Patterns of movement were observed at two geographical scales; while some seals travelled over 100,km, 50% of trips were within 25,km of a haul-out site. These patterns are important for the identification of a marine component to designated protected areas for the species. 5.On average seals returned to the haul-out sites they last used during 40% of trips, indicating a degree of site fidelity, though there was wide variation between different haul-out sites (range 0% to >75%). 6.Low fidelity haul-out sites could form a network of land-based protected areas, while high fidelity sites might form appropriate management units. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    Dolphins in a bottle: abundance, residency patterns and conservation of bottlenose dolphins Tursiops truncatus in the semi-closed eutrophic Amvrakikos Gulf, Greece

    AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 2 2008
    Giovanni Bearzi
    Abstract 1.Boat surveys were conducted between 2002 and 2005 to study bottlenose dolphins living in the 400 km2 Amvrakikos Gulf, western Greece. During 116 survey days, 4705 km of total effort resulted in the individual photo-identification of 106 animals, through long-term natural markings on their dorsal fins. 2.Mark,recapture analyses based on the Mth model provided estimates of 82 marked individuals in 2003 (95% CI=80,91), 92 in 2004 (95% CI=86,108) and 98 in 2005 (95% CI=94,110). To include the unmarked portion of the population, the proportion of unmarked individuals was computed based on the number of photographs of marked and unmarked dorsal fins. The mean proportion of unmarked animals in the population was 0.338 (95% CI=0.288,0.389). By adding this to the estimate for marked animals in 2005, considered as the most robust, a total population estimate of 148 individuals (95% CI=132,180) was obtained. 3.Dolphin encounter rates in 2003,2005 did not show significant variations, and averaged 7.2 groups per 100 km or 72.5 individuals per 100 km. Encounter rates within the Gulf were about one order of magnitude greater than those found for bottlenose dolphins in nearby eastern Ionian Sea coastal waters. 4.Mean dolphin density in the Gulf was 0.37 animals km,2. This relatively high density, together with high levels of site fidelity shown by most individuals, was thought to be related primarily to prey availability, particularly of epipelagic schooling fish. 5.The importance of the semi-closed Amvrakikos Gulf for bottlenose dolphins and other threatened species encourages the adoption of measures aimed to conserve its valuable ecosystems and raise the naturalistic profile of the area, while promoting environment-conscious development. Meaningful action includes restoring natural hydrology (e.g. freshwater input from rivers), curtailing pollution from various sources, responsible fisheries and aquaculture management, and control of illegal fishing. Interactions between dolphins and fisheries also deserve careful quantitative investigation. Copyright © 2007 John Wiley & Sons, Ltd. [source]

    Spatial ecology of a threatened python (Morelia spilota imbricata) and the effects of anthropogenic habitat change

    AUSTRAL ECOLOGY, Issue 3 2005
    D. PEARSON
    Abstract Large predators play important ecological roles, but often are sensitive to habitat changes and thus are early casualties of habitat perturbation. Pythons are among the largest predators in many Australian environments, and hence warrant conservation-orientated research. Carpet pythons (Morelia spilota imbricata) have declined across much of south-western Australia presumably because of habitat clearance and degradation. Information on habitat use, home range sizes and movements is needed to plan for the conservation of this important predator. We studied pythons at two study sites (Garden Island and Dryandra Woodland) with markedly different climates, habitat types and disturbance histories. We surgically implanted radio-transmitters in 91 pythons and tracked them for periods of 1 month to 4 years. Dryandra pythons remained inactive inside tree hollows during cooler months (May,September), whereas some (especially small) pythons on Garden Island continued to move and feed. Overall weekly displacements (mean = 100,150 m) were similar at the two study sites and among sex/age classes, except that reproductive females were sedentary during summer while they were incubating eggs. Home ranges averaged 15,20 ha. Adult male pythons had larger home ranges than adult females at Dryandra, but not at Garden Island. Radio-tracked snakes at Dryandra exhibited high site fidelity, returning to previously occupied logs after long absences and reusing tree hollows for winter shelter. Many of the logs used by snakes had been felled during plantation establishment >70 years ago, with little subsequent regeneration of source trees. In contrast, Garden Island snakes usually sheltered under dense shrubs. Habitat usage was similar among different sex/age classes of snakes at each site, except that juvenile pythons were more arboreal than adults. Although carpet pythons demonstrate great flexibility in habitat use, certain habitat elements appear critical for the persistence of viable populations. Fire plays a central role in this process, albeit in complex ways. For example, low-intensity fires reduce the availability of hollow logs on the ground at Dryandra and fail to regenerate shrub thickets required by prey species. Paradoxically, high-intensity fires stimulate shrub thickets and fell trees creating new logs , but might also threaten overwinter trees. Thus, the impact of disturbances (such as wildfires) on the viability of python populations will be mediated in complex ways by alteration to important microhabitats such as vegetation cover or log availability. At Dryandra, landscape management should include occasional fire events to generate new logs as well as shrub thickets used by prey. Strategic burning may also be required at Garden Island to regenerate some vegetation communities. [source]