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Point Counts (point + count)
Selected AbstractsFactors influencing Willow Tit Poecile montanus site occupancy: a comparison of abandoned and occupied woodsIBIS, Issue 2007ALEX J. G. LEWIS The British Willow Tit Poecile montanus kleinschmidti underwent a decline of 85% between 1970 and 2003. The cause of this decline is unknown. However, several hypotheses have been put forward to account for it: competition from other tit species, predation by Great Spotted Woodpeckers Dendrocopos major and habitat change. In order to test these, woods that are currently occupied by Willow Tits were paired with woods (within 50 km) that had been abandoned by Willow Tits five or more years previously. Point counts for other tit species (potential competitors) and woodpecker species (potential predators) were carried out at ten evenly spaced points throughout each wood. Habitat variables were collected within a 50-m radius of where a Willow Tit was located (in the occupied woods) or where maps showed a Willow Tit had been located (for abandoned woods). No evidence was found for differences in numbers of potential competitor or potential predator species in abandoned and occupied woods. Soil water content was found to be higher at occupied sites. No other habitat features differed between the two categories of site. The drying up of British woods could therefore be implicated in the Willow Tit decline and this warrants further investigation. [source] Patterns of density, diversity, and the distribution of migratory strategies in the Russian boreal forest avifaunaJOURNAL OF BIOGEOGRAPHY, Issue 11 2008Russell Greenberg Abstract Aim, Comparisons of the biotas in the Palaearctic and Nearctic have focused on limited portions of the two regions. The purpose of this study was to assess the geographic pattern in the abundance, species richness, and importance of different migration patterns of the boreal forest avifauna of Eurasia from Europe to East Asia as well as their relationship to climate and forest productivity. We further examine data from two widely separated sites in the New World to see how these conform to the patterns found in the Eurasian system. Location, Boreal forest sites in Russia and Canada. Methods, Point counts were conducted in two to four boreal forest habitats at each of 14 sites in the Russian boreal forest from near to the Finnish border to the Far East, as well as at two sites in boreal Canada. We examined the abundance and species richness of all birds, and specific migratory classes, against four gradients (climate, primary productivity, latitude, and longitude). We tested for spatial autocorrelation in both dependent and independent variables using Moran's I to develop spatial correlograms. For each migratory class we used maximum likelihood to fit models, first assuming uncorrelated residuals and then assuming spatially autocorrelated residuals. For models assuming unstructured residuals we again generated correlograms on model residuals to determine whether model fitting removed spatial autocorrelation. Models were compared using Akaike's information criterion, adjusted for small sample size. Results, Overall abundance was highest at the eastern and western extremes of the survey region and lowest at the continent centre, whereas the abundance of tropical and short-distance migrants displayed an east,west gradient, with tropical migrants increasing in abundance in the east (and south), and short-distance migrants in the west. Although overall species richness showed no geographic pattern, richness within migratory classes showed patterns weaker than, but similar to, their abundance patterns described above. Overall abundance was correlated with climate variables that relate to continentality. The abundances of birds within different migration strategies were correlated with a second climatic gradient , increasing precipitation from west to east. Models using descriptors of location generally had greater explanatory value for the abundance and species-richness response variables than did those based on climate data and the normalized difference vegetation index (NDVI). Main conclusions, The distribution patterns for migrant types were related to both climatic and locational variables, and thus the patterns could be explained by either climatic regime or the accessibility of winter habitats, both historically and currently. Non-boreal wintering habitat is more accessible from both the western and eastern ends than from the centre of the boreal forest belt, but the tropics are most accessible from the eastern end of the Palaearctic boreal zone, in terms of distance and the absence of geographical barriers. Based on comparisons with Canadian sites, we recommend that future comparative studies between Palaearctic and Nearctic faunas be focused more on Siberia and the Russian Far East, as well as on central and western Canada. [source] A six-month randomized controlled trial of exercise and pyridostigmine in the treatment of fibromyalgiaARTHRITIS & RHEUMATISM, Issue 2 2008K. D. Jones Objective A subset of fibromyalgia (FM) patients have a dysfunctional hypothalamic,pituitary,insulin-like growth factor 1 (IGF-1) axis, as evidenced by low serum levels of IGF-1 and a reduced growth hormone (GH) response to physiologic stimuli. There is evidence that pyridostigmine (PYD) improves the acute response of GH to exercise in FM patients. The purpose of this study was to evaluate the clinical effectiveness of 6 months of PYD and group exercise on FM symptoms. Methods FM patients were randomized to 1 of the following 4 groups: PYD plus exercise, PYD plus diet recall but no exercise, placebo plus exercise, and placebo plus diet recall but no exercise. The primary outcome measures were the visual analog scale (VAS) score for pain, tender point count, and total myalgic score. Secondary outcome measures were the total score on the Fibromyalgia Impact Questionnaire (FIQ) and FIQ VAS scores for individual symptoms (fatigue, poor sleep, stiffness, and anxiety), as well as quality of life (QOL) and physical fitness (lower body strength/endurance, upper and lower body flexibility, balance, and time on the treadmill). Results A total of 165 FM patients completed baseline measurements; 154 (93.3%) completed the study. The combination of PYD and exercise did not improve pain scores. PYD groups showed a significant improvement in sleep and anxiety in those who completed the study and in QOL in those who complied with the therapeutic regimen as compared with the placebo groups. Compared with the nonexercise groups, the 2 exercise groups demonstrated improvement in fatigue and fitness. PYD was generally well tolerated. Conclusion Neither the combination of PYD plus supervised exercise nor either treatment alone yielded improvement in most FM symptoms. However, PYD did improve anxiety and sleep, and exercise improved fatigue and fitness. We speculate that PYD may have improved vagal tone, thus benefiting sleep and anxiety; this notion warrants further study. [source] Conservation value of degraded habitats for forest birds in southern Peninsular MalaysiaDIVERSITY AND DISTRIBUTIONS, Issue 5 2006Kelvin S.-H. ABSTRACT Clearance of tropical forest for agricultural purposes is generally assumed to seriously threaten the survival of forest species. In this study, we quantified the conservation value, for forest bird species, of three degraded habitat types in Peninsular Malaysia, namely rubber tree plantations, oil palm plantations, and open areas. We surveyed these degraded habitats using point counts to estimate their forest bird species richness and abundance. We assessed whether richness, abundance, and activities of different avian dietary groups (i.e. insectivores and frugivores) varied among the habitats. We identified the critical habitat elements that accounted for the distribution of forest avifauna in these degraded habitats. Our results showed that these habitats harboured a moderate fraction of forest avifauna (approximately 46,76 species) and their functions were complementary (i.e. rubber tree plantations for moving; open habitats for perching; shrubs in oil palm plantations for foraging). In terms of species richness and abundance, rubber tree plantations were more important than oil palm plantations and open habitats. The relatively high species richness of this agricultural landscape was partly due to the contiguity of our study areas with extensive forest areas. Forecasts of forest-species presence under various canopy cover scenarios suggest that leaving isolated trees among non-arboreal crops could greatly attract relatively tolerant species that require tree canopy. The conservation value of degraded habitats in agricultural landscapes seems to depend on factors such as the type of crops planted and distance to primary forest remnants. [source] Genetic estimates of contemporary effective population size in an endangered butterfly indicate a possible role for genetic compensationEVOLUTIONARY APPLICATIONS (ELECTRONIC), Issue 1 2010Emily V. Saarinen Abstract The effective population size (Ne) is a critical evolutionary and conservation parameter that can indicate the adaptive potential of populations. Robust estimates of Ne of endangered taxa have been previously hampered by estimators that are sensitive to sample size. We estimated Ne on two remaining populations of the endangered Miami blue butterfly, a formerly widespread taxon in Florida. Our goal was to determine the consistency of various temporal and point estimators on inferring Ne and to determine the utility of this information for understanding the role of genetic stochasticity. We found that recently developed ,unbiased estimators' generally performed better than some older methods in that the former had more realistic Ne estimates and were more consistent with what is known about adult population size. Overall, Ne/N ratios based on census point counts were high. We suggest that this pattern may reflect genetic compensation caused by reduced reproductive variance due to breeding population size not being limited by resources. Assuming Ne and N are not heavily biased, it appears that the lack of gene flow between distant populations may be a greater genetic threat in the short term than the loss of heterozygosity due to inbreeding. [source] Fire disturbance disrupts co-occurrence patterns of terrestrial vertebrates in Mediterranean woodlandsJOURNAL OF BIOGEOGRAPHY, Issue 5 2006Maurizio Sarà Abstract Aim, This paper uses null model analysis to explore the pattern of species co-occurrence of terrestrial vertebrate fauna in fire-prone, mixed evergreen oak woodlands. Location, The Erico,Quercion ilicis of the Mediterranean belt (50,800 m a.s.l.) in the Madonie mountain range, a regional park in northern Sicily (37°50, N, 14°05, E), Italy. Methods, The stratified sampling of vertebrates in a secondary succession of recent burned areas (BA, 1,2 years old), intermediate burned areas (INT, 4,10 years old) and ancient burned areas (CNB, > 50 years old), plus forest fragments left within burned areas (FF, 1,2 years old) permitted the comparison of patterns of species co-occurrence using a set of separate presence/absence matrices. First, the breeding avifauna derived from standardized point counts was analysed using Stone & Roberts'C -score, and by a null model algorithm (fixed/equiprobable). Secondly, the analysis was repeated using all vertebrate species recorded in the succession. Results, Sixty-five species were recorded in the 2-year study period in the four sample treatments. Birds were found to make up the largest component (63%) of the recorded assemblage. The BA treatment had the lowest species richness, followed in order by the small, medium and large FFs, and then by the CNBs. For both analyses (birds and total vertebrates), the C -scores were quite small and not significantly different from those that could be expected by chance in the BA and INT burned areas; this indicates a random co-occurrence among vertebrates of those assemblages. Contrariwise, for both analyses in the CNBs, the C -scores were large and significantly different from the simulated indices, thereby indicating a non-random co-occurrence pattern (segregation) of vertebrates in the undisturbed woodlands. In addition, C -score values for the surviving FFs show a significant aggregation of species. Main conclusions, The null model analyses highlighted a new aspect of fire disturbance in Mediterranean woodland ecosystems: the disruption in patterns of co-occurrence in the terrestrial vertebrate community. Wildfire alters community organization, inducing, for at least 10 years, a random aggregate of species. Communities re-assemble themselves, showing the occurrence of species segregation at least 50 years after fire. [source] The invasive red swamp crayfish as a predictor of Eurasian bittern density in the Camargue, FranceJOURNAL OF ZOOLOGY, Issue 1 2007B. Poulin Abstract Few data exist on the relationships between food levels and breeding density of the Eurasian bittern Botaurus stellaris, a vulnerable species of high-priority concern in Europe. Concurrent data were obtained on male bittern density and relative food abundance over a 3-year period in two wetlands totalling 2500 ha of Mediterranean reed marsh enclosing 25% of the French bittern population. Food abundance was estimated by sampling up to 25 hydrological units using a beach seine in early June of 2002, 2003 and 2004. The density of booming males in each hydrological unit was obtained by point counts and acoustic triangulation in May of the same years. The impact of food abundance on male bittern density was assessed by general regression models using a forward stepwise procedure with mosquitofish Gambusia affinis, carp Cyprinus carpio, other fish species, amphibians, red swamp crayfish Procambarus clarkii and other invertebrates as prey groups. Of these, only to crayfish abundance was bittern density related, contributing to 45% of the variance observed. When the impact of water level was taken into account, the relative abundance of crayfish explained 56% of the inter-annual differences in bittern density. Because crayfish are rich in calcium and well adapted to fluctuating hydroperiods alternating with drought intervals, they provide a good food source for the bitterns throughout the breeding season at the study sites. The loss of diversity and degradation reported from macrophyte-dominated marshes following crayfish invasion does not seem to apply to reed-dominated wetlands. It is further suggested that the recent increase in bittern numbers in the Camargue, while other French populations were decreasing, could in part be related to red swamp crayfish abundance. [source] The conservation value for birds of cacao plantations with diverse planted shade in Tabasco, MexicoANIMAL CONSERVATION, Issue 2 2000Russell Greenberg We surveyed birds in cacao (Theobroma cacao) plantations in the state of Tabasco, Mexico. The shade canopy was planted by farmers and consisted of approximately 60 species of trees with no single dominant species. Canopy height averaged 15 m and the structure was multi-storied. We conducted 220 ten minute, 25 m radius point counts for birds and detected 1550 individuals from 81 species. The average number of birds/point and the expected diversity in a fixed number of individuals within the cacao surveyed were well within the range of other lowland habitats, including agricultural sites, that we have surveyed previously in neighbouring Chiapas. In the Tabascan cacao, the migrant group was composed, in part, of forest species, and dimorphic species were represented primarily by males, which in other areas are known to dominate forest or forest-like habitats. In contrast to the composition of migrant species, we found few resident forest specialists in Tabascan cacao. Instead, the tropical resident group was composed of large-bodied generalist species that use small patches of trees in open habitats. These results (moderate diversity, low numbers of forest specialists) differ from the few studies completed in ,rustic' cacao systems located near large tracts of forest. The planted shade cacao agroecosystem , at least in the absence of nearby forest , may have a limited value for conserving lost tropical forest bird diversity, but it provides habitat for woodland-associated migratory species. Our results also indicate that the planted shade cacao plantations supported few small omnivorous or frugivorous species, probably because cacao itself, as well as the dominant shade trees, produce primarily mammal or wind dispersed fruit and seeds. [source] | |||||||||||||