PArental Care Strategies (PACS) of arctic shorebirds: consequences of the interplay between abiotic conditions and predator-prey interactions on breeding success – PACS

There is ample evidence that climate changes (CC) are among the most influential drivers of biodiversity, and predicting the consequences of CC on species and their ecosystems is a major challenge for ecologists. Most studies have concentrated on the effects of CC of phenology and physiology on organisms, as well as changes in the distribution and range shifts of species. By contrast, detailed studies of animal behaviour and species interactions remain scarce. Thus, in the current context of CC, understanding the relative contributions of abiotic and biotic factors in driving the behaviour of species remains among the major questions for ecologists. Abiotic factors (here including temperature, precipitations, snow regimes and, by extension, primary productivity) directly impact breeding success of birds, and are expected to induce modulation of their parental care strategies (PACS). However, PACS can also be influenced by biotic interactions like predation. Furthermore, individual responses (incl. PACS) to changes in abiotic factors and predator-prey interactions are often studied separately, while they may act in synergy. Thus, understanding the complex interplay between abiotic factors and biotic interactions is essential to fully understand how individuals cope with their changing environment and to what extent they can respond to ongoing CC.
In the Arctic, two main strategies of PACS co-occur in shorebirds during incubation: biparental care, in which both parents share incubation duties, and uniparental care, in which only one adult incubates the eggs. Time allocation during incubation period is likely to result from a trade-off between maintaining egg temperature, energy requirements of the breeding adults and nest predation risk.
Because the Arctic region is warming more rapidly than any other on Earth, and the changes in temperatures and snowmelt are affecting a broad array of resident and migratory arctic organisms, this region and its species are highly exposed to CC and particularly suited to answer our questions. Furthermore, the limited number of interacting species, as well as the strong seasonality and short summer (i.e., most species are only interacting a few weeks or months a year), makes biotic interactions easier to study in the Arctic than elsewhere. The small and well characterized trophic network of shorebirds, lemming and arctic fox, is an ideal ecological system to study predator-prey interactions and their sensitivity to CC at different temporal, spatial and organizational scales.
Taking advantage of these unique conditions and multisite approach, with 6 sites distributed across the Arctic with different abiotic conditions and predation risk, the overall objectives of this study are to model the optimal PACS routines which maximize the reproductive success of the birds at the scale of the season (task1), to investigate in the field the responses (in terms of PACS) of shorebirds (genus Calidris) to changes in abiotic conditions (task 2), and predation risk (task 3), and then to integrate these results in a synergetic model (task 4) that will assess the respective and combined contributions of abiotic factors and inter-specific interactions in explaining observed predation rates on shorebird nests.