Predicted climate‐induced reductions in scavenging in eastern North America

Abstract

Scavenging is an important function within ecosystems where scavengers remove organic matter, reduce disease, stabilize food webs, and generally make ecosystems more resilient to environmental changes. Global change (i.e., changing climate and increasing human impact) is currently influencing scavenger communities. Thus, understanding what promotes species richness in scavenger communities can help prioritize management actions. Using a long‐term dataset from camera traps deployed with animal carcasses as bait along a 1881 km latitudinal gradient in the Appalachian Mountains of eastern USA, we investigated the relative impact of climate and humans on the species richness and diversity of vertebrate scavengers. Our most supported models for both mammalian and avian scavengers included climatic, but not human, variables. The richness of mammalian and avian scavengers detected was highest during relatively warm (5–10°C) and dry (100–150 mm precipitation) winters, when food was likely limited and both reliance on and detection of carrion was high. The diversity of mammalian and avian scavengers detected was highest under drier conditions. We then used these results to project the future species richness of scavengers that would be detected within our sampling area and under the climate scenario of 2070 (emissions level RCP8.5). Our predictions suggest up to 80% and 67% reductions, respectively, in the richness of avian and mammalian scavengers that would be detected at baited sites. Climate‐induced shifts in behavior (i.e., reduction in scavenging, even if present) at this scale could have cascading implications for ecosystem function, resilience, and human health. Further, our study highlights the importance of conducting studies of scavenger community dynamics within ecosystems across wide spatial gradients within temperate environments. More broadly, these findings build upon our understanding of the impacts of climate‐induced adjustments in behavior that can likely have negative impacts on systems at a large scale.

Poleward expansion of Turkey Vultures (Cathartes aura) under future conditions

“…Thus, further investigation into how competition could be impacting Turkey Vultures in the future is required. The consumption of large food items (e.g., white-tailed deer [ Odocoileus virginianus ]) by Turkey Vultures in their current range is predicted to decrease in the future (Marneweck et al 2021), which could result in more distinct dietary partitioning where Turkey Vultures focus on smaller food items to avoid competitive interactions. However, given the potential poleward expansion, this could provide new opportunities for Turkey Vultures to scavenge large food items at high/low latitudes, which could have implications for carcass access by other facultative scavengers, such as corvids (e.g., Canada Jays [ Perisoreus canadensis ]) or smaller raptors (e.g., Crested Caracaras [ Caracara plancus ]).…”

“…Therefore, human population growth and associated increased availability of anthropogenic food subsidies could support the range expansion of Turkey Vultures and support year-round residents in the north when natural food sources would otherwise be difficult to find. Recent findings suggest a decline in the occurrence of Turkey Vultures scavenging large carcasses under future winter conditions across the eastern USA (Marneweck et al 2021). Thus, there is uncertainty about how Turkey Vultures will respond to future global change scenarios.…”

Comparative analysis of gut DNA viromes in wild and captive Himalayan vultures

“…Specifically, approximately 73% of vulture species are at a high risk of extinction, with 77% of global populations experiencing dramatic declines in the late 20th century ( Buechley and Sekercioglu, 2016 ). The decline is attributed to various factors such as dietary toxins [residual veterinary drugs in livestock carcasses ( Swan et al, 2006 ; Adawaren et al, 2018 ) and poisonous baits ( Margalida et al, 2019 ; van den Heever et al, 2019 )], habitat loss, lack of food resources, nest abandonment, low reproductive rate, hunting for traditional medicine or belief-based use ( Mckean et al, 2013 ), climate change ( Marneweck et al, 2021 ), heavy metal bioaccumulation ( Yamac et al, 2019 ; Bassi et al, 2021 ), and collisions with wind turbines ( de Lucas et al, 2012 ). Consequently, political measures, such as banning the veterinary use of diclofenac in India, Pakistan, Nepal, and Bangladesh, as well as establishing supplementary feeding stations, are being implemented for vulture protection and conservation efforts ( Cortes-Avizanda et al, 2010 ; Moleon et al, 2014 ; Morales-Reyes et al, 2018 ; Blanco et al, 2019 ).…”