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Breeding Habitat (breeding + habitat)
Selected AbstractsOne Hundred Fifty Years of Change in Forest Bird Breeding Habitat: Estimates of Species DistributionsCONSERVATION BIOLOGY, Issue 6 2005LISA A. SCHULTE aptitud del hábitat; ecología aviar; ecología de paisaje; planificación de conservación Abstract:,Evaluating bird population trends requires baseline data. In North America the earliest population data available are those from the late 1960s. Forest conditions in the northern Great Lake states (U.S.A.), however, have undergone succession since the region was originally cut over around the turn of the twentieth century, and it is expected that bird populations have undergone concomitant change. We propose pre-Euro-American settlement as an alternative baseline for assessing changes in bird populations. We evaluated the amount, quality, and distribution of breeding bird habitat during the mid-1800s and early 1990s for three forest birds: the Pine Warbler (Dendroica pinus), Blackburnian Warbler (D. fusca), and Black-throated Green Warbler (D. virens). We constructed models of bird and habitat relationships based on literature review and regional data sets of bird abundance and applied these models to widely available vegetation data. Original public-land survey records represented historical habitat conditions, and a combination of forest inventory and national land-cover data represented current conditions. We assessed model robustness by comparing current habitat distribution to actual breeding bird locations from the Wisconsin Breeding Bird Atlas. The model showed little change in the overall amount of Pine Warbler habitat, whereas both the Blackburnian Warber and the Black-throated Green Warbler have experienced substantial habitat losses. For the species we examined, habitat quality has degraded since presettlement and the spatial distribution of habitat shifted among ecoregions, with range expansion accompanying forest incursion into previously open habitats or the replacement of native forests with pine plantations. Sources of habitat loss and degradation include loss of conifers and loss of large trees. Using widely available data sources in a habitat suitability model framework, our method provides a long-term analysis of change in bird habitat and a presettlement baseline for assessing current conservation priority. Resumen:,La evaluación de tendencias de las poblaciones de aves requiere de datos de referencia. En Norte América, los primeros datos disponibles de poblaciones son del final de la década de 1960. Sin embargo, las condiciones de los bosques en los estados de los Grandes Lagos (E.U.A.) han experimentado sucesión desde que la región fue talada en los inicios del siglo veinte, y se espera que las poblaciones de aves hayan experimentado cambios concomitantes. Proponemos que se considere al período previo a la colonización euro americana como referencia alternativa para evaluar los cambios en las poblaciones de aves. Evaluamos la cantidad, calidad y distribución del hábitat para reproducción de tres especies de aves de bosque (Dendroica pinus, D. fusca y D. virens) a mediados del siglo XIX e inicios del XX. Construimos modelos de las relaciones entre las aves y el hábitat con base en la literatura y conjuntos de datos de abundancia de aves y los aplicamos a los datos de vegetación ampliamente disponibles. Los registros topográficos de tierras públicas originales representaron las condiciones históricas del hábitat, y una combinación de datos del inventario forestal y de cobertura de suelo representaron las condiciones actuales. Evaluamos la robustez del modelo mediante la comparación de la distribución de hábitat actual con sitios de reproducción de aves registrados en el Wisconsin Breeding Bird Atlas. El modelo mostró poco cambio en la cantidad total de hábitat de Dendroica pinus, mientras que tanto D. fusca como D. virens han experimentado pérdidas sustanciales de hábitat. Para las especies examinadas, la calidad del hábitat se ha degradado desde antes de la colonización y la distribución espacial del hábitat cambió entre ecoregiones, con la expansión del rango acompañando la incursión de bosques en hábitats anteriormente abiertos o el reemplazo de bosques nativos con plantaciones de pinos. Las fuentes de pérdida y degradación de hábitats incluyen la pérdida de coníferas y de árboles grandes. Mediante la utilización de fuentes de datos ampliamente disponibles en un modelo de aptitud de hábitat, nuestro método proporciona un análisis a largo plazo de los cambios en el hábitat de aves y una referencia precolonización para evaluar prioridades de conservación actuales. [source] Optimal conservation planning for migratory animals: integrating demographic information across seasonsCONSERVATION LETTERS, Issue 3 2010Justin Sheehy Abstract Conservation strategies for migratory animals are typically based on ad-hoc or simple ranking methods and focus on a single period of the annual cycle. We use a density-dependent population model to examine one-time land purchase strategies for a migratory population with a breeding and wintering grounds. Under equal rates of habitat loss, we show that it is optimal to invest more, but never solely, in the habitat with the higher density dependence to habitat cost ratio. When there are two habitats that vary in quality within a season, the best strategy is to invest only in one habitat. Whether to purchase high- or low-quality habitat depends on the general life history of the species and the ratio of habitat quality to habitat cost. When carry-over effects are incorporated, it is almost always optimal to invest in high-quality habitat during the season that produces the carry-over effect. We apply this model to a threatened warbler population and show the optimal strategy is to purchase more breeding than wintering habitat despite the fact that breeding habitat is over ten times more expensive. Our model provides a framework for developing year-round conservation strategies for migratory animals and has important implications for long-term planning and management. [source] Topographic spatial characterisation of grey seal Halichoerus grypus breeding habitat at a sub-seal size spatial grainECOGRAPHY, Issue 3 2001S. D. Twiss Expansion within breeding colonies may critically depend upon the availability of suitable breeding habitat. Here we use topographic modelling in a GIS to characterise suitable pupping habitat and accurately predict the pattern of colonisation in an expanding grey seal breeding colony-the Isle of May (Scotland), We use high resolution images from large format aerial photographs of the colony to generate sub-metre accurate Digital Terrain Models (DTMs), GIS modelling with these DTMs provides topographic measures of elevation, slope and ease of access to sea and freshwater pools at a 2 m grid cell size. Seal locations during the 1994 breeding season, with sex-age class, were also digitised from the same images. We examine how the physical attributes of cells (locations) with and without pups differ and identify areas suitable for pupping but remaining unoccupied during 1994. We predict patterns of future colonisation by characterising areas differentiated by the densities of pups within 5 m grid cells and identifying areas, both occupied or unoccupied, with a potential for increased future pupping densities. Our predictions were tested by examining pup distributions observed in the 1998 breeding season. Occupied sites were significantly closer to freshwater pools and access to the sea (p < 0.001) than unoccupied sites suggesting that proximity to water may restrict colony expansion before all areas of suitably flat terrain are occupied. All pup density classes occurred in sites with similar slope values and distance to pools. However, higher pupping densities occurred closer to access points (p = 0.014). Pup densities observed in 1998 revealed that our 1994 predictions were accurate (p < 0.0001). Only 12% of 466 grid cells had higher densities in 1998 than predicted, of which 88% differed by only 1 pup. These incorrectly classified cells occurred at the expanding edge of the colony (in a more topographically homogenous area) and at the main access points from the sea (major traffic zones). These results demonstrate the value of the accurate quantification of topographic parameters at the appropriate spatial grain (in this case below the size of the individual) for use in habitat classification and predictions of habitat utilization. [source] Breeding habitat use and the future management of the critically endangered Southern Corroboree FrogECOLOGICAL MANAGEMENT & RESTORATION, Issue 2009David Hunter Summary The Southern Corroboree Frog (Pseudophryne corroboree) is one of Australia's most critically endangered frog species. The species occurs entirely within Kosciuszko National Park, which has a history of cattle grazing (up to the 1970s). A consequence of cattle grazing has been a significant reduction in the extent of montane and sub-alpine peat-bog systems that the species uses as breeding habitat. Furthermore, climate change and associated increased wildfire frequency is expected to further reduce the extent and quality of peat bogs throughout the Australian Alps. In this study, we investigated habitat selection for breeding pools and nest sites within peat-bog systems in order to inform the conservation management of the species and guide other management practices being undertaken in peat bogs where this species occurs. Occupancy of breeding males at bog pools was found to be positively associated with increasing pool area, water depth and mid-day temperature, and negatively associated with extent of bare substrate. The majority of breeding pools identified were ephemeral. Nest sites within vegetation where males call and where females deposit their eggs were located at mid-elevations in a range of vegetation types, with the majority of nests being within moss and sedge dominated by Sphagnum cristatum and Empodisma minor. We also found that male nest sites were not randomly distributed within the edges of pools, but were more often located in areas of loose vegetation. These results highlight the potential sensitivity of the Southern Corroboree Frog to predicted changes in peat-bog systems resulting from climate change such as earlier drying and a possible reduction in the size of bog pools. A monitoring programme focused on key features of the breeding habitat should be undertaken to provide a basis for developing and assessing management actions implemented in peat bogs occupied by this species. [source] Habitat selection by Ortolan Buntings Emberiza hortulana in post-fire succession in Catalonia: implications for the conservation of farmland populationsIBIS, Issue 4 2009MYLES H. M. MENZ The Ortolan Bunting Emberiza hortulana is a long-distance migrant that has suffered major population declines across much of its European breeding range. While northern populations are bound largely to farmland, Mediterranean populations are largely confined to habitats subject to recurrent wildfires. Habitat selection of the Ortolan Bunting was assessed in a recently burnt area in Catalonia at landscape and habitat scales. A Zero-inflated Poisson procedure was used to model the abundance of birds in relation to landscape and habitat variables. The most parsimonious landscape model predicted the highest abundance on south-facing slopes, with a gradient above 10°. The most parsimonious habitat model showed a positive quadratic effect of bare ground and regenerating oak Quercus spp., with predicted optima for abundance around 20,30% and 20% cover, respectively. There was a clear relationship between predicted abundance of the Ortolan Bunting and post-fire regenerating oak shrubs. South-facing, moderately sloping areas were favoured and bare ground was a key feature of the species' habitat. A matrix combining patches of sparse oak shrubs and patches of bare ground appears to be the optimal breeding habitat in the Mediterranean. The maintenance or provision of similar habitat features, especially patches of bare ground, may prove crucial for the conservation of rapidly declining Ortolan Bunting populations on farmland across temperate Europe. [source] Breeding biology and conservation of the Black-vented Shearwater Puffinus opisthomelasIBIS, Issue 4 2003Bradford S. Keitt The Black-vented Shearwater Puffinus opisthomelas is endemic to the Pacific coast of Baja California, Mexico. We studied the breeding biology of this species at Natividad Island in 1997 and 1998. The colony at Natividad Island covers approximately 2.5 km2 and we estimated there to be 114 455 (± 27 520 95% CI) burrows in the colony. In 1997 burrow occupancy was 66.9%, providing a population estimate of 76 570 (± 18 411 95% CI) breeding pairs, representing about 95% of the world's population of this species. In 1997 the peak in egg laying occurred in early March and hatching began on 7 May. The incubation period averaged 51 days (± 6 sd) and chick rearing averaged 69 days (± 3 sd). In 1998 burrow occupancy was lower (19.6%) and nest initiation was later (peak egg laying in mid-April), perhaps a result of El Niño conditions that prevailed in the Eastern Pacific at that time. We calculated that the development of the town and roads on Natividad Island have destroyed over 15% (26 532 burrows) of the breeding habitat on the island. [source] Variation in the growth and survival of Golden Plover Pluvialis apricaria chicksIBIS, Issue 2 2002J. W. Pearce-Higgins The growth of Golden Plover Pluvialis apricaria chicks is modelled in detail for the first time. The pattern of growth is typical of postnatal development in waders, although the mean fledging time of 37 days is slower than would be expected from adult body weight. Bill length and weight at hatching had significant effects on the rate of weight gain shown by 2-day-old chicks, although this effect was not noticeable at 4 days of age. Chick survival was significantly affected by bill length, as a result of the variation in weight gain. The growth of older chicks was positively correlated with mean minimum temperature. The slow rate of growth exhibited by Golden Plover chicks is discussed in relation to breeding habitat and the effects of weather and hatchling biometrics. [source] Parental behaviour of a precocial species: implications for juvenile survivalJOURNAL OF APPLIED ECOLOGY, Issue 4 2009Victoria J. Dreitz Summary 1., Parents determine habitat selection for precocial young by leading their young to foraging areas until the chicks attain full independence. There are potential benefits and costs to reproductive success associated with changing habitats while caring for young. This study investigated the relationship between different types of habitats and their quality on chick survival and brood movements of a declining upland shorebird, the mountain plover Charadrius montanus. 2., From 2004 to 2006, a total of 153 mountain plover broods were monitored on the primary breeding habitats in eastern Colorado, USA; two shortgrass prairie habitats that were either occupied or unoccupied by black-tailed prairie dogs Cynomys ludovicianus and agricultural lands. Habitat quality hypotheses were tested using newly developed statistical applications to estimate survival of chicks and brood movement patterns. 3., Chick survival and brood movements were influenced by habitat. Chick survival over the 30-day brood-rearing period was substantially higher on nesting habitat of shortgrass occupied by prairie dogs compared with agricultural land and shortgrass unoccupied by prairie dogs. The rate of brood movement away from shortgrass with prairie dogs was lower than shortgrass without prairie dogs, but higher than agricultural lands for each year of the study. 4., This study suggests that complex processes influence how different habitats affect brood-rearing activity of mountain plovers. Even though broods moved off nesting habitat of shortgrass occupied by prairie dogs, this habitat had the highest survival rate and is highly important to mountain plover reproductive success. 5.,Synthesis and applications. In order to develop effective conservation strategies, the provision of adequate breeding habitat should include information on patterns of habitat selection for all stages of the breeding cycle, including the nesting and dependent young periods. From a conservation perspective, understanding the habitat use of young birds is critical when population dynamics show great sensitivity to survival of young. Previous studies on mountain plovers have suggested that nest success is similar among shortgrass prairie habitats and agricultural lands. Thus, conservation measures that increase nest success may be ineffective for mountain plovers unless they are accompanied by measures promoting chick survival. [source] Climatic effects on timing of spring migration and breeding in a long-distance migrant, the pied flycatcher Ficedula hypoleucaJOURNAL OF AVIAN BIOLOGY, Issue 5 2005Christiaan Both Climate change has advanced the breeding dates of many bird species, but for few species we know whether this advancement is sufficient to track the advancement of the underlying levels of the food chain. For the long-distance migratory pied flycatcher Ficedula hypoleuca the advancement in breeding time has been insufficient to maintain the synchrony with their main food sources. The timing of arrival in the breeding areas from their African wintering grounds is likely to constrain the advancement of breeding date. We hypothesise that this is because in Africa they cannot predict the advancement of spring in their breeding habitat. However, long-distance migrants may advance their arrival time by migrating faster when circumstances en route are favourable. In this study we show that both arrival and breeding date depend on temperatures at their main North African staging grounds, as well as on temperature at the breeding grounds. Male arrival and average laying date were not correlated, but the positive effect of temperature in North Africa on breeding dates suggests that breeding date is indeed constrained by arrival of females. Long-distance migrants thus are able to adjust arrival and hence breeding by faster spring migration, but the degree of adjustment is probably limited as timing schedules in spring are tight. Furthermore, as climate change is affecting temperatures differently along the migratory flyway and the breeding areas, it is unlikely that arrival dates are advanced at the same rate as the timing of breeding should advance, given the advancement of the underlying levels of the food chain. [source] Species conservation on human-dominated landscapes: the case of crowned crane breeding and distribution outside protected areas in UgandaAFRICAN JOURNAL OF ECOLOGY, Issue 1 2010William Olupot Abstract Species primarily dependent on habitats outside protected areas have to cope with the direct pressure of human utilization or harassment, and the indirect pressure of habitat modification. In Uganda, wetlands mainly used by cranes occur mostly outside protected areas. The country's wetlands are however under heavy modification, and this and other pressures are thought to have reduced crane populations to 10,30% of the number in the early 1970s. From January 2005 to January 2006, we assessed the status of crane breeding and distribution in the country. Breeding and foraging sites were assessed through a nationwide newspaper survey, and visits to wetlands. We established occurrence of 21 nests during the study period, and crane use of 27 out of 30 districts surveyed. Crane harassment and trapping were common during breeding, as was crop damage by cranes. This is the first attempt to show the distribution of crane breeding outside protected areas throughout the country. In addition to maintaining suitable breeding habitat, survival of cranes in Uganda lies in part in community engagement and punishing crimes related to hunting and destruction of nests. Résumé Les espèces qui dépendent principalement d'habitats situés en dehors des aires protégées doivent supporter la pression directe de l'utilisation ou du harassement humains, et la pression indirecte de la modification de l'habitat. En Ouganda, les zones humides que les grues fréquentent le plus souvent se trouvent en dehors des aires protégées. Les zones humides du pays subissent pourtant de lourdes modifications, et ceci, entre autres pressions, est censéêtre ce qui a causé la réduction des populations de grues à 10,30% de ce qu'elles étaient au début des années 1970. De janvier 2005 à janvier 2006, nous avons évalué le statut de la reproduction et de la distribution des grues dans le pays. Les sites de reproduction et de nourrissage ont étéévalués grâce à une étude dans tout le pays via les journaux, et à des visites des zones humides. Nous avons pu établir la présence de 21 nids au cours de l'étude, et la fréquentation par les grues de 27 des 30 districts étudiés. Le harassement et le piégeage des crues ont été fréquents pendant la reproduction, comme l'étaient les dommages causés aux cultures par les grues. Ceci est la première tentative pour montrer la distribution de la reproduction des grues dans le pays en dehors des aires protégées. En plus du maintien d'habitats favorables à la reproduction, la survie des grues en Ouganda repose en partie sur l'implication communautaire dans la conservation des grues et sur le renforcement des mesures de sanctions contre les crimes liés à la chasse et à la destruction des nids. [source] Abundance of Snowy and Wilson's Plovers in the lower Laguna Madre region of TexasJOURNAL OF FIELD ORNITHOLOGY, Issue 4 2007Sharyn L. Hood ABSTRACT Snowy Plovers (Charadrius alexandrinus) and Wilson's Plovers (C. wilsonia) are shorebird species of increasing conservation concern, with populations apparently declining in North America. However, estimates of current populations are needed before initiating long-term monitoring or planning. In 2004, we estimated abundance of breeding Snowy and Wilson's plovers in the lower Laguna Madre region of Texas using occupancy abundance estimation. We made repeated visits to survey plots from April to June, recording the number of adults of both species observed and the amount of suitable breeding habitat within each plot. We considered Bayesian occupancy abundance models with and without habitat covariates to explain the abundance of both species. For both Snowy and Wilson's plovers, the number of birds counted in each plot was influenced by the amount of suitable breeding habitat within the plot (Snowy Plover ,habitat= 0.52, SD = 0.10, 95% CI = 0.33,0.71; Wilson's Plover ,habitat= 0.48, SD = 0.12, 95% CI = 0.24,0.71). Using the habitat covariate models for each species, we estimated that 416 adult Snowy Plovers (95% CI = 394,438) and 279 adult Wilson's Plovers (95% CI = 262,296) were present in our study area. Our results illustrate the use of a relatively new method for abundance estimation, and indicate that the lower Laguna Madre region of Texas is an important breeding area for both Snowy and Wilson's plovers. Given the documented and suspected population declines for Snowy and Wilson's plovers, we recommend protection of their breeding habitats along the coast of Texas from development and degradation resulting from unregulated use. SINOPSIS Charadrius alexandrinus y C. wilsonia son dos especies de playeros que son objeto de preocupación porque sus poblaciones parecen estar disminuyendo en Norte América. Sin embargo, se necesitan estimados poblacionales antes de se comience con su monitoreos a largo alcance o la planificación de su conservación. En el 2004, estimamos la abundancia de ambas especies en la parte baja de la Laguna Madre en Texas utilizando estimados de abundancia. Hicimos visitas repetidas para hacer encuestas en parcelas de abril a junio, contando el número de adultos de ambas especies y la cantidad de hábitat adecuado para cada especie entre cada parcela. Consideramos un modelo de abundancia Bayesiano con y sin covariantes de hábitat para explicar la abundancia de ambas especies. Para ambas especies el número de aves contadas en cada parcela fue influenciado por la cantidad de hábitat reproductivo apropiado dentro de la parcela (C. alexandrinus,habitat= 0.52, SD = 0.10, 95% CI = 0.33 , 0.71; C. wilsonia,habitat= 0.48, SD = 0.12, 95% CI = 0.24 , 0.71). Utilizando el modelo de covarianza para cada especie, estimamos un total de 416 individuos de C. alexandrinus (95% CI = 394 , 438) y de 279 adultos de C. wilsonia (95% CI = 262 , 296) en nuestra área de estudio. Nuestros resultados ilustran el uso de un método relativamente nuevo para estimar la abundancia. Este indica que la región estudiada en Laguna Madre es de importancia para la reproducción de ambas especies. Dada la documentación y la sospecha fundamentada de la reducción en número de ambas especies, recomendamos la protección de su hábitat reproductivo, del desarrollo urbano y de la degradación resultante del uso sin regulación de la costa en Texas. [source] Inferring colonization history and dispersal patterns of a long-lived seabird by combining genetic and empirical dataJOURNAL OF ZOOLOGY, Issue 4 2010L. C. Young Abstract Identifying biological trends and threats to organisms that make long distance migrations are often the limiting factors in their conservation. Indeed, Laysan albatross Phoebastria immutabilis are highly vagile seabirds, foraging throughout the North Pacific Ocean. Despite mark,recapture data indicating natal philopatry, Laysan albatross recently re-colonized several anthropogenically extirpated breeding locations. At the same time, a breeding population in the north-western Hawaiian Islands was lost to erosion and it was hypothesized that the colonization events were due to displacement rather than dispersal. Nuclear and mitochondrial markers were used in a range wide survey to test whether natal philopatry corresponded to population structure in Laysan albatross, and to determine whether recent colonization events were a result of displacement from vanishing breeding habitat. Five microsatellite loci found little population structure (FST=0.01, P=0.001), and sequences from the mitochondrial control region revealed low population structure (,ST=0.05, P<0.001). The results were consistent with male-mediated dispersal and strong, but not absolute, philopatry by females. Mixed stock analyses and banding records from the newly colonized sites indicated contributions from multiple source populations, which contradicted the displacement hypothesis of a single source population and instead supported species-wide dispersal from all source colonies. High genetic diversity (,=0.045, h=0.989), rapid colonization, and great dispersal potential bode well for the conservation of Laysan albatross. However, it may be necessary to protect high-island nesting sites, preserve genetic diversity and maintain breeding populations in the face of projected sea level rises and persistent bycatch. [source] Winter commingling of populations of migratory species can cause breeding range underpopulationOIKOS, Issue 12 2007Alexander M. Mills We build a model with large-scale demographic consequences for migratory species. The model operates where four elements co-occur, and we rely on empirical research using migratory birds to demonstrate them. First, breeding ranges have internal structure flowing from natal philopatry. Second, fecundity varies geographically. Third, populations of different breeding provenances commingle during winter. And fourth, a population-limiting carrying capacity operates during winter. In the absence of breeding season population-limitation, only the breeding population with maximum fecundity persists. Consequently, some potential breeding areas that offer suitable and productive habitat are bereft of breeding birds because of the interplay between the geographical fecundity gradient and the shared winter quarters. Where breeding season population-limitation also plays a role for at least one population, one (or more) breeding population becomes permanently depressed, resulting in a density well below the carrying capacity of the productive breeding habitat that is occupied. In either case, not all populations fare equally well, despite net positive breeding season productivity. Changes in winter carrying capacity, for example habitat degradation in winter quarters, can lead to uneven effects on geographically defined breeding populations, even though there has been no change in the circumstances of the breeding range. [source] Spatial distribution of vectors of Ross River virus and Barmah Forest virus on Russell Island, Moreton Bay, QueenslandAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 4 2002Jason AL Jeffery Abstract We used a network of 20 carbon dioxide- and octenol-supplemented light traps to sample adult mosquitoes throughout Russell Island in southern Moreton Bay, south-east Queensland. Between February and April 2001, an estimated 1365 564 adult female mosquitoes were collected. In contrast to an average catch of 9754 female mosquitoes per trap night on Russell Island, reference traps set on Macleay Island and on the mainland returned average catches of 3172 and 222, respectively. On Russell Island, Ochlerotatus vigilax (Skuse), Coquillettidia linealis (Skuse), Culex annulirostris Skuse and Verrallina funerea (Theobald), known or suspected vectors of Ross River (RR) and/or Barmah Forest (BF) viruses, comprised 89.6% of the 25 taxa collected. When the spatial distributions of the above species were mapped and analysed using local spatial statistics, all were found to be present in highest numbers towards the southern end of the island during most of the 7 weeks. This indicated the presence of more suitable adult harbourage sites and/or suboptimal larval control efficacy. As immature stages and the breeding habitat of Cq. linealis are as yet undescribed, this species in particular presents a considerable impediment to proposed development scenarios. The method presented here of mapping the numbers of mosquitoes throughout a local government area allows specific areas that have high vector numbers to be defined. [source] Nesting Habitat of the Lilac-crowned Parrot in a Modified Landscape in MexicoBIOTROPICA, Issue 3 2009Tiberio C. Monterrubio-Rico ABSTRACT Parrot populations are being increasingly pressured to occupy modified or fragmented landscapes, yet little is known of the habitat requirements of most species, particularly with regard to the effects on breeding habitat. We evaluated nesting habitat of the lilac-crowned parrot Amazona finschi in the modified landscape of coastal Michoacan in Mexico. We located 90 parrot nests in 12 tree species in Michoacan, with lilac-crowned parrots presenting a narrow niche-breadth of tree species used for nesting. Considering an additional 82 nest trees recorded for lilac-crowned parrots in Jalisco, we determined a 51 percent similarity in cavity resource use by parrots in the two dry forest regions. Overall, the predominant nest tree species with 76 percent of nests were Astronium graveolens, Piranhea mexicana, Brosimum alicastrum, and Tabebuia spp., all characteristic of semi-deciduous forest. Only 8 percent of nests occurred in trees characteristic of deciduous forest. Parrots utilized large trees with canopy level cavities as nest sites, and preferred conserved semi-deciduous forest for nesting, with fewer nests than expected in deciduous forest and transformed agricultural land. Nest areas in semi-deciduous forest occurred on significantly steeper terrain, as remnant semi-deciduous forest is restricted to steep ridges and canyons. Those parrot nests in modified habitats and forest patches were located near to continuous forest, with nest trees in open agricultural land being significantly closer to continuous forest than nests in disturbed forest patches. These results demonstrate the importance of conserved semi-deciduous forest as breeding habitat for the threatened, endemic lilac-crowned parrot, making wild populations of the species vulnerable to the high rate of transformation and fragmentation of tropical dry forest. RESUMEN Las poblaciones de Psitácidos están siendo presionadas a ocupar paisajes modificados, sin embargo poco se conoce sobre los requerimientos de hábitat para la mayoría de las especies, particularmente con respecto a los efectos sobre sus hábitats de anidación. Evaluamos el hábitat de anidación del loro corona lila (Amazona finschi) en el paisaje modificado de la costa de Michoacán en México. Localizamos 90 sitios de anidación en 12 especies de árboles en Michoacan, encontrando que el loro corona lila presentó una estrecha amplitud de nicho en el uso de especies de árboles para anidar. Considerando un adicional 82 árboles-nido del loro corona lila en Jalisco, determinamos un 51% de similitud en utilización del recurso de cavidades por los loros en los dos regiones de bosque seco. Los árboles claves, con 76% de los nidos, fueron Astronium graveolens, Piranhea mexicana, Brosimum alicastrum, y Tabebuia spp., todos característicos del bosque subcaducifolio. Solo 8% de los nidos se encontraron en arboles características del bosque caducifolio. Los loros utilizaron árboles grandes con cavidades en el dosel como sitios de anidación, y prefirieron el bosque subcaducifolio conservado para anidar, con un menor número de nidos que lo esperado en el bosque caducifolio y tierras agropecuarias. Las áreas de anidación en bosque subcaducifolio ocurrieron sobre pendientes significativamente más inclinadas, ya que los remanentes de este tipo de vegetación están actualmente restringidos a pendientes inclinadas y cañadas. Aquellos nidos en hábitats modificados y parches pequeños de vegetación se localizaron cerca de áreas de bosque continuo, con los árboles-nido que ocurrieron en terrenos agropecuarios significativamente más cerca de los bosques continuos, que los que ocurrieron en fragmentos de bosques perturbados. Estos resultados destacan la importancia del bosque subcaducifolio conservado como hábitat de anidación para esta especie de loro endémico y amenazado, haciendo a sus poblaciones silvestres vulnerables al alto nivel de transformación y fragmentación del bosque tropical seco. [source] Integrating species life-history traits and patterns of deforestation in amphibian conservation planningDIVERSITY AND DISTRIBUTIONS, Issue 1 2010C. G. Becker Abstract Aim, To identify priority areas for amphibian conservation in southeastern Brazil, by integrating species life-history traits and patterns of deforestation. Location, State of São Paulo, Brazil. Methods, We used the software Marxan to evaluate different scenarios of amphibian conservation planning. Our approach differs from previous methods by explicitly including two different landscape metrics; habitat split for species with aquatic larvae, and habitat loss for species with terrestrial development. We evaluated the effect of habitat requirements by classifying species breeding habitats in five categories (flowing water, still water permanent, still water temporary, bromeliad or bamboo, and terrestrial). We performed analyses using two scales, grid cells and watersheds and also considered nature preserves as protected areas. Results, We found contrasting patterns of deforestation between coastal and inland regions. Seventy-six grid cells and 14 watersheds are capable of representing each species at least once. When accounting for grid cells already protected in state and national parks and considering species habitat requirements we found 16 high-priority grid cells for species with one or two reproductive habitats, and only one cell representing species with four habitat requirements. Key areas for the conservation of species breeding in flowing and permanent still waters are concentrated in southern state, while those for amphibians breeding in temporary ponds are concentrated in central to eastern zones. Eastern highland zones are key areas for preserving species breeding terrestrially by direct or indirect development. Species breeding in bromeliads and bamboos are already well represented in protected areas. Main conclusions, Our results emphasize the need to integrate information on landscape configuration and species life-history traits to produce more ecologically relevant conservation strategies. [source] Tooth size and skin thickness in mature sockeye salmon: evidence for habitat constraints and variable investment between the sexesECOLOGY OF FRESHWATER FISH, Issue 3 2006S. P. Johnson Abstract ,, Pacific salmon develop many sexually dimorphic features at maturity, and the extent of development varies among populations. In this study, we compared a suite of traits including body length, body depth, jaw length, tooth size and skin mass in male and female sockeye salmon breeding in beach and creek habitats. Both tooth size and skin mass varied positively with body length. Within each of the breeding habitats, males had longer teeth than females, and within each sex, beach spawners had longer teeth than creek spawners. Males also had heavier skin than females in each habitat but, unlike the case with tooth size, creek spawners showed a much stronger relationship between skin mass and body length than did beach spawners. Tooth length was positively related to jaw length and skin mass among individuals within a given sex and habitat. Taken together, these results suggested that variation in tooth size parallels variation in other sexually dimorphic traits. Males and beach spawners tend to exhibit large trait values relative to females and creek spawners, and ,well-endowed' individuals displayed high values of all traits rather than a trade-off as might occur if investment in one trait compromised investment in others. However, the finding that creek fish tended to have thicker skin for a given body length than did beach fish suggested that factors other than merely defense against conspecifics during battle, such as abrasion and desiccation resistance in small streams, may influence the evolution of skin mass in mature sockeye salmon. [source] Parental behaviour of a precocial species: implications for juvenile survivalJOURNAL OF APPLIED ECOLOGY, Issue 4 2009Victoria J. Dreitz Summary 1., Parents determine habitat selection for precocial young by leading their young to foraging areas until the chicks attain full independence. There are potential benefits and costs to reproductive success associated with changing habitats while caring for young. This study investigated the relationship between different types of habitats and their quality on chick survival and brood movements of a declining upland shorebird, the mountain plover Charadrius montanus. 2., From 2004 to 2006, a total of 153 mountain plover broods were monitored on the primary breeding habitats in eastern Colorado, USA; two shortgrass prairie habitats that were either occupied or unoccupied by black-tailed prairie dogs Cynomys ludovicianus and agricultural lands. Habitat quality hypotheses were tested using newly developed statistical applications to estimate survival of chicks and brood movement patterns. 3., Chick survival and brood movements were influenced by habitat. Chick survival over the 30-day brood-rearing period was substantially higher on nesting habitat of shortgrass occupied by prairie dogs compared with agricultural land and shortgrass unoccupied by prairie dogs. The rate of brood movement away from shortgrass with prairie dogs was lower than shortgrass without prairie dogs, but higher than agricultural lands for each year of the study. 4., This study suggests that complex processes influence how different habitats affect brood-rearing activity of mountain plovers. Even though broods moved off nesting habitat of shortgrass occupied by prairie dogs, this habitat had the highest survival rate and is highly important to mountain plover reproductive success. 5.,Synthesis and applications. In order to develop effective conservation strategies, the provision of adequate breeding habitat should include information on patterns of habitat selection for all stages of the breeding cycle, including the nesting and dependent young periods. From a conservation perspective, understanding the habitat use of young birds is critical when population dynamics show great sensitivity to survival of young. Previous studies on mountain plovers have suggested that nest success is similar among shortgrass prairie habitats and agricultural lands. Thus, conservation measures that increase nest success may be ineffective for mountain plovers unless they are accompanied by measures promoting chick survival. [source] Abundance of Snowy and Wilson's Plovers in the lower Laguna Madre region of TexasJOURNAL OF FIELD ORNITHOLOGY, Issue 4 2007Sharyn L. Hood ABSTRACT Snowy Plovers (Charadrius alexandrinus) and Wilson's Plovers (C. wilsonia) are shorebird species of increasing conservation concern, with populations apparently declining in North America. However, estimates of current populations are needed before initiating long-term monitoring or planning. In 2004, we estimated abundance of breeding Snowy and Wilson's plovers in the lower Laguna Madre region of Texas using occupancy abundance estimation. We made repeated visits to survey plots from April to June, recording the number of adults of both species observed and the amount of suitable breeding habitat within each plot. We considered Bayesian occupancy abundance models with and without habitat covariates to explain the abundance of both species. For both Snowy and Wilson's plovers, the number of birds counted in each plot was influenced by the amount of suitable breeding habitat within the plot (Snowy Plover ,habitat= 0.52, SD = 0.10, 95% CI = 0.33,0.71; Wilson's Plover ,habitat= 0.48, SD = 0.12, 95% CI = 0.24,0.71). Using the habitat covariate models for each species, we estimated that 416 adult Snowy Plovers (95% CI = 394,438) and 279 adult Wilson's Plovers (95% CI = 262,296) were present in our study area. Our results illustrate the use of a relatively new method for abundance estimation, and indicate that the lower Laguna Madre region of Texas is an important breeding area for both Snowy and Wilson's plovers. Given the documented and suspected population declines for Snowy and Wilson's plovers, we recommend protection of their breeding habitats along the coast of Texas from development and degradation resulting from unregulated use. SINOPSIS Charadrius alexandrinus y C. wilsonia son dos especies de playeros que son objeto de preocupación porque sus poblaciones parecen estar disminuyendo en Norte América. Sin embargo, se necesitan estimados poblacionales antes de se comience con su monitoreos a largo alcance o la planificación de su conservación. En el 2004, estimamos la abundancia de ambas especies en la parte baja de la Laguna Madre en Texas utilizando estimados de abundancia. Hicimos visitas repetidas para hacer encuestas en parcelas de abril a junio, contando el número de adultos de ambas especies y la cantidad de hábitat adecuado para cada especie entre cada parcela. Consideramos un modelo de abundancia Bayesiano con y sin covariantes de hábitat para explicar la abundancia de ambas especies. Para ambas especies el número de aves contadas en cada parcela fue influenciado por la cantidad de hábitat reproductivo apropiado dentro de la parcela (C. alexandrinus,habitat= 0.52, SD = 0.10, 95% CI = 0.33 , 0.71; C. wilsonia,habitat= 0.48, SD = 0.12, 95% CI = 0.24 , 0.71). Utilizando el modelo de covarianza para cada especie, estimamos un total de 416 individuos de C. alexandrinus (95% CI = 394 , 438) y de 279 adultos de C. wilsonia (95% CI = 262 , 296) en nuestra área de estudio. Nuestros resultados ilustran el uso de un método relativamente nuevo para estimar la abundancia. Este indica que la región estudiada en Laguna Madre es de importancia para la reproducción de ambas especies. Dada la documentación y la sospecha fundamentada de la reducción en número de ambas especies, recomendamos la protección de su hábitat reproductivo, del desarrollo urbano y de la degradación resultante del uso sin regulación de la costa en Texas. [source] Development time and survival of Verrallina funerea (Theobald) (Diptera: Culicidae) immatures and other brackish water mosquito species in southeast Queensland, AustraliaAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 3 2005Jason A L Jeffery Abstract,Verrallina funerea (Theobald) is a brackish water mosquito that is recognised as an important pest and vector in southeast Queensland, Australia. Immature development time and survival of Ve. funerea was defined in the laboratory in response to a range of temperatures (17,34°C) and salinities (0,35 parts per thousand (p.p.t)). The expression of autogeny in this species was also assessed. Salinity only had a slight effect on mean development time from hatching to adult emergence (7.0,7.4 d at salinities of 0, 17.5 and 31.5 p.p.t) and survival was uniformly high (97.5,99.0%). Mean development times were shorter at 26, 29 and 32°C (7.0, 6.8 and 6.8 d, respectively) and longest at 17°C (12.2 d). The threshold temperature (t) was 5.8°C and the thermal constant (K) was 142.9 degree-days above t. Survival to adulthood decreased from >95% (at 17,29°C) to 78% (at 32°C) and 0% (at 34°C). No expression of autogeny was observed. Immature development times of Ve. funerea, Ochlerotatus vigilax (Skuse) and Oc. procax (Skuse) were then determined under field conditions at Maroochy Shire. Following tide and rain inundation, cohorts of newly hatched larvae were monitored daily by dipping, and time until pupation was noted. Tidal inundation triggered hatching of Ve. funerea and Oc. vigilax larvae whereas Oc. procax larvae were found only after rain inundation. Estimates of Ve. funerea and Oc. vigilax field development times were similar (8,9 d) while Oc. procax development time was slightly longer (9,10 d). Based on these survey results, control activities targeting Ve. funerea must be initiated 4 d (if using Bacillus thuringiensis var. israelensis de Barjac) or 5 d (if using s -methoprene) after inundation. However, Casuarina glauca Sieber canopy and branchlets covering breeding habitats may present a problem for the penetration of such treatments. [source] Vector competence of Coquillettidia linealis (Skuse) (Diptera: Culicidae) for Ross River and Barmah Forest virusesAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 4 2002Jason AL Jeffery AbstractCoquillettidia linealis is a severe pest on some of the Moreton Bay islands in Queensland, Australia, but little is known of its breeding habitats and biology. Because of its high abundance and its association with Ross River (RR) and Barmah Forest (BF) viruses by field isolation, its vector competence was evaluated in the laboratory by feeding dilutions of both viruses in blood. For RR, Cq. linealis was of comparable efficiency to Ochlerotatus vigilax (Skuse), recognised as being a major vector. Results were as follows for Cq. linealis and Oc. vigilax, respectively: dose to infect 50%, 102.2 and <101.7 CCID50/mosquito; 88% and 90% disseminated infection at 4 days postinfection; transmission at 4 days with rates of 68,92% and 25,60%. For BF dose to infect 50%, 102.7 and 102.0; disseminated infection rates on first transmission day (day 6), 40% and 70%; transmission rates of 8,16% and 0,10%. As a capillary-tube method was used rather than suckling mice to demonstrate transmission, transmission rates may be underestimates. This, the first study of the vector competence of Cq. linealis in Australia, demonstrates that this species deserves control on the southern Moreton Bay islands. [source] | |||||||||||||||||||||||||