Flexibility in a changing arctic food web: Can rough‐legged buzzards cope with changing small rodent communities?

Abstract

Indirect effects of climate change are often mediated by trophic interactions and consequences for individual species depend on how they are tied into the local food web. Here we show how the response of demographic rates of an arctic bird of prey to fluctuations in small rodent abundance changed when small rodent community composition and dynamics changed, possibly under the effect of climate warming. We observed the breeding biology of rough‐legged buzzards (Buteo lagopus) at the Erkuta Tundra Monitoring Site in southern Yamal, low arctic Russia, for 19 years (1999–2017). At the same time, data on small rodent abundance were collected and information on buzzard diet was obtained from pellet dissection. The small rodent community experienced a shift from high‐amplitude cycles to dampened fluctuations paralleled with a change in species composition toward less lemmings and more voles. Buzzards clearly preferred lemmings as prey. Breeding density of buzzards was positively related to small rodent abundance, but the shift in small rodent community lead to lower numbers relative to small rodent abundance. At the same time, after the change in small rodent community, the average number of fledglings was higher relative to small rodent abundance than earlier. These results suggest that the buzzard population adapted to a certain degree to the changes in the major resource, although at the same time density declined. The documented flexibility in the short‐term response of demographic rates to changes in structure and dynamics of key food web components make it difficult to predict how complex food webs will be transformed in a warmer Arctic. The degree of plasticity of functional responses is indeed likely to vary between species and between regions, depending also on the local food web context.

Can reindeer husbandry management slow down the shrubification of the Arctic?

“…In addition, the inclusion of herbivory pressures from small herbivores such as voles and lemmings (Olofsson et al 2014) could help elucidate plant-herbivore interaction in the region. However, literature suggests that, compared to other regions in the Arctic such as Fennoscandia, small rodent abundance has been relatively low at our study site for the last 20 years (Fufachev et al 2019). The use of multispectral optical satellite imagery to map the dynamics of tundra vegetation moreover limited the scope of our investigation.…”

Anthropogenic impacts on the demographics of Arctic-breeding birds

“…In recent times climate change has instigated a breakdown in lemming cycles, some changing in amplitude and others even disappearing. Breeding Rough-legged Buzzard (Buteo lagopus) densities in Yamal, Russia, decreased following disruption to the existing lemming cycle and shifts in the small rodent community composition, although, unexpectedly, breeding success in the remaining pairs actually increased (Fufachev et al 2019). However, Aharon-Rotman et al (2015) could not identify a strong link between breeding success and lemming regulated predation pressure in Russian and Alaskan wader populations nor impacts on wader population trends.…”

Assessing molar wear in narrow-headed voles as a proxy for diet and habitat in a changing Arctic

“…There is no place this is more evident than the Arctic. Rodent densities are especially sensitive to changing climate (e.g., Ehrich et al 2017;Fufachev et al 2019;Gilg et al 2009;Ims et al 2011;Morris and Dupuch 2012). This makes them excellent model mammals for monitoring changes in the tundra biome (Christensen et al 2013), and researchers associated with the Circumpolar Biodiversity Monitoring Program have focused on rodents over the past two decades at 49 sites across the Arctic (38 of which are currently active), from Alaska to Canada, Greenland, Fennoscandia, and Russia (Ehrich et al 2020).…”

“…Moreover, it presents a continuous biogeographic gradient between bioclimatic subzones C and E, from the border between low and high Arctic to forest-tundra ecotone (see Walker et al 2005). Yamal is among the best studied areas for tundra ecology in the Russian Arctic, with long-term uninterrupted research since Soviet times (e.g., Dunaeva 1948) and expanding studies of terrestrial ecosystems today (Ehrich et al 2017;Fufachev et al 2019;Sokolov et al 2012Sokolov et al , 2016Sokolova et al 2014). Furthermore, unprecedented support from the Government of Yamal-Nenets Autonomous District has funded state-of-the art scientific infrastructure and research initiatives at Yamal.…”

“…At each site, three traps were baited with raisins and rolled oats at each corner of a 15 × 15 m permanent quadrat following small-quadrat field protocol (Myllymäki et al 1971), i.e., 12 traps per quadrat for two nights, with 8 (Kharp), 12 (Sabetta) and 18 (Erkuta) replications of quadrats at each habitat to sample microhabitat variability. The trapping protocol used is described in detail in Sokolova et al (2014) and in Fufachev et al (2019). At Kharp, sampling usually occurs in June and September, at Erkuta in June and August, and at Sabetta in July.…”