Royal Society for the Protection of Birds

About: Royal Society for the Protection of Birds is a nonprofit organization based out in Sandy, United Kingdom. It is known for research contribution in the topics: Population & Biodiversity. The organization has 670 authors who have published 1425 publications receiving 88006 citations. The organization is also known as: RSPB & Plumage League.

Population status and trend of the Critically Endangered Montserrat Oriole

Abstract: Summary Many island endemics are of great conservation concern due to small range and population sizes. The Montserrat Oriole Icterus oberi is a forest passerine endemic to the Caribbean island of Montserrat, where recent volcanic activity has destroyed a large proportion of suitable forest habitat. From 1997 to 2000 the Montserrat Oriole population declined dramatically even in the remaining forest habitat, leading to its classification as ‘Critically Endangered’. We present trend estimates of the Montserrat Oriole population from 2000 to 2013, and estimate the world population size in 2012 based on repeat point counts and beta-binomial mixture models. Montserrat Orioles recovered between 2003 and 2005, and we found no evidence for a continuing population decline. However, there was large uncertainty around trend estimates, and the power to detect a shallow negative trend was very low. Based on the comparison of count data at 42 points, the Montserrat Oriole population in 2013 was less than half as large as in 1998. To improve future trend estimates a new monitoring design was introduced in 2011, and applied to all subpopulations of the species in 2012. The world population in 2012 was estimated to hold between 307 (95% credible interval 212–503) and 690 birds (476–1131) birds in the two forest fragments on Montserrat, depending on whether the sampling area around each point count was assumed to encompass 100 m or 150 m. Based on these estimates, the Montserrat Oriole currently does not meet the IUCN criteria for ‘Critically Endangered’, and we recommend a revision of the species’ conservation status.

Higher spring temperatures increase food scarcity and limit the current and future distributions of crossbills

Abstract: Editor: Helen Regan Abstract Aim: Understanding how climate affects species distributions remains a major challenge, with the relative importance of direct physiological effects versus biotic interactions still poorly understood. We focus on three species of resource specialists (crossbill Loxia finches) to assess the role of climate in determining the seasonal availability of their food, the importance of climate and the occurrence of their food plants for explaining their current distributions, and to predict changes in their distributions under future climate change scenarios. Location: Europe. Methods: We used datasets on the timing of seed fall in European Scots pine Pinus sylvestris forests (where different crossbill species occur) to estimate seed fall phenology and climate data to determine its influence on spatial and temporal variation in the timing of seed fall to provide a link between climate and seed scarcity for crossbills. We used largescale datasets on crossbill distribution, cover of the conifers relied on by the three crossbill species and climate variables associated with timing of seed fall, to assess their relative importance for predicting crossbill distributions. We used species distribution modelling to predict changes in their distributions under climate change projections for 2070. Results: We found that seed fall occurred 1.5–2 months earlier in southern Europe than in Sweden and Scotland and was associated with variation in spring maximum temperatures and precipitation. These climate variables and area covered with conifers relied on by the crossbills explained much of their observed distributions. Projections under global change scenarios revealed reductions in potential crossbill distributions, especially for parrot crossbills. Main conclusions: Ranges of resource specialists are directly influenced by the presence of their food plants, with climate conditions further affecting resource availability and the window of food scarcity indirectly. Future distributions will be determined by tree responses to changing climatic conditions and the impact of climate on seed fall phenology.

Territory occupancy and breeding success of Peregrine Falcons Falco peregrinus at various stages of population recovery

Abstract: Organochlorine pesticides disrupted reproduction and killed many raptorial birds, and contributed to population declines during the 1940s to 1970s. We sought to discern whether and to what extent territory occupancy and breeding success changed from the pesticide era to recent years in a resident population of Peregrine Falcons Falco peregrinus in southern Scotland using long-term (1964–2015) field data and multi-state, multi-season occupancy models. Peregrine territories that were occupied with successful reproduction in one year were much more likely to be occupied and experience reproductive success in the following year, compared with those that were unoccupied or occupied by unsuccessful breeders in the previous year. Probability of territory occupancy differed between territories in the eastern and western parts of the study area, and varied over time. The probability of occupancy of territories that were unoccupied and those that were occupied with successful reproduction during the previous breeding season generally increased over time, whereas the probability of occupancy of territories that were occupied after failed reproduction decreased. The probability of reproductive success (conditional on occupancy) in territories that were occupied during the previous breeding season increased over time. Specifically, for territories that had been successful in the previous year, the probability of occupancy as well as reproductive success increased steadily over time; these probabilities were substantially higher in recent years than earlier, when the population was still exposed to direct or residual effects of organochlorine pesticides. These results are consistent with the hypothesis that progressive reduction, followed by a complete ban, in the use of organochlorine pesticides improved reproductive success of Peregrines in southern Scotland. Differences in the temporal pattern of probability of reproductive success between south-eastern and south-western Scotland suggest that the effect of organochlorine pesticides on Peregrine reproductive success and/or the recovery from pesticide effects varied geographically and was possibly affected by other factors such as persecution.

Overcoming hermit-crab interference during rodent-baiting operations: a case study from Henderson Island, South Pacific

Abstract: Context Rat (Rattus spp.) eradication operations in the tropics are often put at risk by the presence of land crabs, in particular hermit crabs (Coenobitidae), which consume toxic bait and thereby render it unavailable to rats. Aims We estimated hermit-crab densities in areas of high abundance, assessed crab bait consumption rates and determined the required baiting application rate to ensure that 100% of Pacific rats (Rattus exulans) consumed bait in areas with high crab densities on Henderson Island, South Pacific. Methods Crab densities and rat densities were estimated through Distance sampling of crabs and mark–recapture of rats. Non-toxic rhodamine-dyed cereal bait pellets were spread by hand at varying densities within four study plots and rats were captured 12 days later and examined for the presence of rhodamine biomarker dye. Key results Crab densities (primarily Coenobita perlatus) varied between beaches from 130 crabs ha–1 to 1370 crabs ha–1, with rats occurring at respective densities of 28 and 7 rats ha–1 on these beaches. Estimated bait consumption rate of C. perlatus was 3.8 g crab–1 day–1. In total, 100% of rats were positive for rhodamine-dyed bait, despite the high densities of crabs present. Conclusions The results support the prospects for a successful rat eradication on Henderson Island, although careful consideration must be given to the potential impact of an eradication on non-target species. The estimated bait consumption rate by C. perlatus found in the present study may allow other eradication operations to make initial calculations of the required baiting densities to overcome interference from this species.