Analysis of Population Trends for Farmland Birds Using Generalized Additive Models

Fewster, Rachel M.; Buckland, Stephen T.; Siriwardena, G.; Baillie, Stephen R.; Wilson, Jeremy D.

doi:10.2307/177286

Cited by 142 publications

(261 citation statements)

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“…Due to tremendous changes that have occurred in agricultural practices since the mid-twentieth century, plant and animal species traditionally associated with farmland have declined massively in most regions of the Western world (Andreasen et al 1996;Benton et al 2002;Bignal and McCraken 1996;Böhning-Gaese and Bauer 1996;Chamberlain and Fuller 2001;Chamberlain et al 2000;Donald et al 2001;Fewster et al 2000;Fuller et al 1995;Gillings and Fuller 1998;Jackson and Jackson 2002;Siriwardena et al 1998;Smart et al 2000;Sotherton and Self 2000;Wilson et al 1999). Recently, there have been widespread incentives to promote cultivation methods that are less detrimental to wildlife, such as biological control and organic farming, which have progressively enabled the ecological quality of these habitats to be improved (Chamberlain et al 1999;Dennis et al 1994;de Snoo 1999;Freemark and Kirk 2001;Robinson and Sutherland 2002).…”

Section: Introductionmentioning

confidence: 99%

Foraging ecology and reproductive biology of the Stonechat Saxicola torquata: comparison between a revitalized, intensively cultivated and a historical, traditionally cultivated agro-ecosystem

2008

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An effective strategy to reintegrate biodiversity within otherwise intensively cultivated agroecosystems is to create set-aside and wildflower areas. It remains largely unknown, however, whether the ecological performance of an agroecosystem revitalized in this manner is comparable-from a species' population biology perspective-to traditionally exploited farmland. To address this question we compared, during two successive years, the trophic ecology and breeding performance of an insectivorous, indicator passerine (the Stonechat Saxicola torquata) in a revitalized intensively cultivated farmland (RIC) and a traditional, extensively cultivated farmland (TEC) in southern Switzerland. The chicks' diet and prey abundance did not differ between the RIC and TEC, with orthopterans, caterpillars (Lepidoptera) and coleopterans predominating (approx. 80% of diet biomass). Although Stonechat pairs initiated more broods in TEC than in the RIC, reproductive success (number of fledglings/territory 9 year) did not differ significantly between the TEC and RIC. The chicks' condition (body mass) was slightly better in TEC than in RIC, while no such effect could be shown for chick constitution (tarsus length) in either year. The inter-site (RIC vs. TEC) variation fell well within the inter-annual variation of breeding parameters, indicating that environmental stochasticity could be a greater determinant of reproductive output and young quality than agroecosystem type. Although in need of replication, these results suggest that incentives for setting aside farmland and creating wildflower areas within agroecosystems may not only enhance plant and invertebrate diversity, as has been demonstrated earlier, but can also support functioning populations of vertebrates situated at higher trophic levels along the food chain.

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Section: Introductionmentioning

confidence: 99%

Foraging ecology and reproductive biology of the Stonechat Saxicola torquata: comparison between a revitalized, intensively cultivated and a historical, traditionally cultivated agro-ecosystem

2008

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“…Monitoring programs are among the most important data sources for assessing temporal changes in biodiversity (e.g., Fewster et al 2000;van Strien et al 2001;Gregory et al 2005). Most monitoring data available in the literature show that both partridges and rabbits have followed stable or even negative trends since the mid1990s, which clearly contradicts the pattern suggested by national bag records.…”

Section: Resultsmentioning

confidence: 99%

Is the interaction between rabbit hemorrhagic disease and hyperpredation by raptors a major cause of the red-legged partridge decline in Spain?

et al. 2011

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Hyperpredation can be described as a restrictive case of apparent competition where an increased number of primary prey species indirectly induces the decrease of the secondary prey species through numerical response of predators to the primary prey dynamics. It has been proposed that rabbit hemorrhagic disease (RHD), which decimated populations of European wild rabbit (Oryctolagus cuniculus) in Spain, led to prey switching by raptors towards red-legged partridges (Alectoris rufa) causing declines in their populations as a peculiar case of hyperpredation.We have reviewed field studies that disagree with estimates (based on bag records) of recent increases of rabbit and partridge numbers in Spain. Because of an increase in releases of farm-reared animals, there is doubt about the use of bag records to accurately estimate population trends in recent decades. We also provide new data and discuss some analytical considerations related to the temporal and spatial scales that might affect the interpretation of data. Finally, we discuss why studies associated with raptor food habits, predator population dynamics and predator distribution suggest that diet data are not sufficient to link patterns and processes. Although we agree that the RHD outbreak has markedly affected rabbit populations, which has indirectly affected many other species in the Iberian Peninsula, we consider that hyperpredation mediated by raptors has not been clearly demonstrated. In contrast, endorsing the hypothesis of raptor-mediated hyperpredation without sufficient proof may have conflictive consequences if we consider the increased persecution of raptors in recent decades in Spain.

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“…In GAMs, the linear equation predictors that are associated with the GLMs are replaced by a more general additive predictor which allows the change in abundance over time to follow any smooth curve and not just a linear form (Fewster et al 2000). In order to capture the non-linear form of data over time, GAMs use a variety of smoothing techniques which were originally developed for smoothing scatterplots.…”

Section: Data Analysis Methodsmentioning

confidence: 99%

“…In order to capture the non-linear form of data over time, GAMs use a variety of smoothing techniques which were originally developed for smoothing scatterplots. Such smoothers are the kernel smoothers, weighted regression smoothers and running-median smoothers (Fewster et al 2000). In the present study, smoothing splines were used which satisfy a penalised least squares criterion.…”

Section: Data Analysis Methodsmentioning

confidence: 99%

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Systematic Raptor Monitoring as conservation tool: 12 year results in the light of landscape changes in Dadia-Lefkimi-Soufli National Park

Poirazidis¹

2017

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Dadia-Lefkimi-Soufli National Park forms part of the Natura 2000 network in a region of Greece and represents one of the most diverse landscapes for raptors (birds of prey) breeding in Europe. It is adjacent to Bulgaria and Turkey and is a renowned biodiversity hotspot. WWF Greece established a Systematic Raptor Monitoring scheme in this area in 2001.This study summarises the results of the first 12 years of monitoring in the National Park. Overall, 25 to 27 raptor species were recorded by pooling data, of which20 species reproduced in the National Park. Raptors with continuous presence in the National Park exhibited stable, species-specific inter-annual variation. An average of 348±15.4 raptor territories were distributed throughout the National Park for all species. The Common buzzard (Buteo buteo) and the Shorttoed eagle (Circaetus gallicus) were the most common species year-round, followed by the Lesser-spotted eagle (Clanga pomarina) and Booted eagle (Aquila pennata). The Long-legged buzzard (Buteo rufinus), Honey buzzard (Pernis apivorus) and Egyptian vulture (Neophron percnopterus) exhibited a noticeable drop in population numbers over the study period. A significant new entry was the re-appearance of the Whitetailed eagle (Haliaeetus albicilla), which was recorded breeding again in the region after a 21-year absence. Species trends, along with their ecological traits, are discussed with respect to landscape changes in Dadia NP and minimum viable population and territory thresholds are proposed to outline essential conservation issues. Although a multi-year balance of the total number of occupied territories for all species was recorded, the number of common species increased compared to specialist species which had smaller, de- RESEARCH ARTICLE Launched to accelerate biodiversity conservation A peer-reviewed open-access journalKonstantinos Poirazidis / Nature Conservation 22: 17-50 (2017) 18 clining populations. The abandoning of traditional livestock farming, which induces an increase in closedcanopy forest coverage, might have led to the decline of the Lesser-spotted eagle, Long-legged buzzard and Honey buzzard numbers. Additional pressure is added from specialist forest dwelling raptors which are favoured by this change in habitat. The results of this study are expected to provide useful insights to facilitate conservation and management decisions about raptors and their habitat in this region.

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Analysis of Population Trends for Farmland Birds Using Generalized Additive Models

Cited by 142 publications

References 0 publications

Foraging ecology and reproductive biology of the Stonechat Saxicola torquata: comparison between a revitalized, intensively cultivated and a historical, traditionally cultivated agro-ecosystem

Foraging ecology and reproductive biology of the Stonechat Saxicola torquata: comparison between a revitalized, intensively cultivated and a historical, traditionally cultivated agro-ecosystem

Is the interaction between rabbit hemorrhagic disease and hyperpredation by raptors a major cause of the red-legged partridge decline in Spain?

Systematic Raptor Monitoring as conservation tool: 12 year results in the light of landscape changes in Dadia-Lefkimi-Soufli National Park

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