Reindeer carcasses provide foraging habitat for insectivorous birds of the alpine tundra

Abstract

On August of 2016, 323 wild tundra reindeer (Rangifer tarandus) were struck by lightning on southern Norway, killing virtually the entire herd. During fieldwork for parallel studies in 2017, we opportunistically registered the occurrence and behavior of avian species on carcasses from this mass die-off. Several passerine species other than corvids were observed actively foraging on arthropods that are typically associated with carcass decomposition, such as blowfly (Calliphoridae sp.) adults and larvae. In decreasing order of abundance, five passerine species (excluding corvids) were observed taking arthropods at the site: the Meadow Pipit (Anthus pratensis, least concern), Northern Wheatear (Oenanthe oenanthe, least concern), Common ReedBunting(Emberizaschoeniclus, near threatened), Bluethroat (Lusciniasvecica, near threatened), and Lapland Bunting (Calcarius lapponicus, vulnerable) (status according to IUCN). Previous studies on these passerines have documented a very sharp decline in their abundance in Norway. The insect abundance associated with ungulate carcasses may provide an important food resource for such species, and may impact their life history, fitness, and eventually population dynamics. This mechanism, however, has received almost no attention from the scientific community, and warrants further investigation.

Infection risk associated with carnivore carcasses may govern trophic interactions between maggots and insectivorous passerine birds

“…carcass-maggot cycle [23]) on an ecological timescale. As previously reported [24], juvenile birds frequently preyed on maggots. The degree of aversion is likely determined by the balance between nutritional benefits and the cost of infection risk [25,26].…”

From death comes life: Large vertebrate carrion enhances seedling establishment in clonal ericaceous shrubs

“…Crucially for the proposed pathway of directed endozoochorous dispersal, animals with ericaceous seed dispersal potential constituted 94% of all observations at carcass plots. These included common scavenging omnivores and smaller passerine birds attracted to carcasses by the abundant insect life there (Badia et al., 2019). Passerine birds can be particularly effective seed disperses of ericaceous seeds (García‐Rodríguez et al., 2022), even generating deterministic seed deposition patterns (Arnberg et al., 2023).…”

“…Crucially for the proposed pathway of directed endozoochorous dispersal, animals with ericaceous seed dispersal potential constituted 94% of all observations at carcass plots. These included common scavenging omnivores and smaller passerine birds attracted to carcasses by the abundant insect life there (Badia et al, 2019).…”

Fear the reaper: ungulate carcasses may generate an ephemeral landscape of fear for rodents

“…These processes are underpinned by ecological and species interactions [4][5][6]. Animals take advantage of carrion either through the direct consumption of detritus or indirectly by feeding on arthropod 'blooms' in and around carcass sites [7][8][9].…”

“…only carcass density was used from a range of search radii as a covariate, and an interaction with year (2017 and 2018) was added to assess how each rodent presence, bird abundance and mammal abundance responses varied between years and with carcass density. Model selection (AICc) was used across each response and with the search radius of carcass density ranging(1,2,3,4,5,6,7,8,9,10,15,20,30,40,50, 100, 200 m). A residual autocovariate (RAC) was used in model structures for mesopredator and bird abundance responses, as those models depicted spatial autocorrelation (SAC; Moran's I test) in the residuals.…”