Population vulnerability to climate change linked to timing of breeding in boreal ducks

Abstract

Identifying and understanding why traits make species vulnerable to changing climatic conditions remain central problems in evolutionary and applied ecology. We used spring snow cover duration as a proxy for phenological timing of wetland ecosystems, and examined how snow cover duration during spring and during the entire snow season affected population dynamics of duck species breeding in the western boreal forest of North America, 1973America, -2007 We predicted that population level responses would differ among duck species, such that late-nesting species with reduced flexibility in their timing of breeding, i.e. scaup (Aythya spp.) and scoter (Melanitta spp.), would be more strongly affected by changing snow cover conditions relative to species better able to adjust timing of breeding to seasonal phenology, i.e. mallard (Anas platyrhynchos) and American wigeon (Anas americana). Population growth rates of scaup and scoter were positively linked to spring snow cover duration; after accounting for effects of density dependence, larger populations resulted after springs with long snow cover duration than after springs with short snow cover duration. In contrast, population growth rates of mallard and wigeon were either negatively or only weakly associated with snow cover duration. Duck population models were then incorporated with snow cover duration derived from climate model simulations under the A2 emission scenario, and these predictions suggested that latenesting duck species will experience the most severe population declines. Results are consistent with a hypothesis that the gradual climatic warming observed in the western boreal forest of North America has contributed to and may continue to exacerbate population declines of scaup and scoter.

Variability and change in the Canadian cryosphere

“…With respect to terrestrial ecosystems, snow cover, permafrost conditions, surface hydrology, and vegetation are all inter-related. For example, recent dramatic reductions in Arctic spring snow cover duration reported in and Derksen and Brown (2011) have direct effects on wildlife (for example, see Drever et al 2011). Shorter snow cover seasons are consistent with an extension of the growing season over the Arctic as discussed in Jia et al (2009), and are consistent with earlier peak stream flow, a more rapid recessional limb, and higher peak runoff volume, as reported by Shiklomanov and Lammers (2009).…”

Predicting Climate Change Impacts to the Canadian Boreal Forest

“…Previous research has suggested that drier and warmer conditions may lead to a 70%-90% loss of wetlands in the Hudson Plains [76]. Reduced duration of snow cover, associated with predicted increases in minimum greenness and decreased seasonality, will negatively impact some duck species in boreal wetlands [77]. For example, reduced flexibility in timing of breeding has been predicted to impact population levels of species such as scaups (Aythya spp.)…”

Spatiotemporal distributions of intestinal helminths in female lesser scaupAythya affinisduring spring migration from the upper Midwest, USA

“…The differing helminth infracommunity structures observed herein occurred within a small geographical scale relative to the annual cycle of scaup, indicating that these hosts may experience frequent and rapid changes in intestinal parasite infracommunities, which may be strongly related to intermediate hosts present in diets. Global climate change and increased habitat fragmentation are of increasing concern for conservation efforts (Austin et al, 2006;Drever et al, 2012) and may affect the dispersal of hosts and parasites, thereby altering their interactions and disease dynamics at different scales (Holt & Boulinier, 2005). Considering the temporal proximity of the spring migration and breeding seasons, energetic and behavioural costs of immune responses to varying helminth infections may lead to reduced survival and/or productivity (Hanssen et al, 2004;Stafford et al, 2014).…”