Born to cope with climate change? Experimentally manipulated hatching time does not affect duckling survival in the mallard Anas platyrhynchos

Abstract

Two main hypotheses proposed to explain the seasonal decline in reproductive performance in birds are (1) deterioration of environmental conditions and (2) lower parental quality of late breeders. Previous experimental work addressing these hypotheses generally have problematic biases pertaining to delay of hatching, costs of re-laying and incubation, as well as variation in the quality of eggs, territories, offspring and parental traits. We address these biases in an experimental test of the timing hypothesis (i.e.(1) above) in a precocial bird. Using a 2-year cross-over design and game-farm mallard (Anas platyrhynchos) eggs originating from a number of hens and a standardised delay procedure, we introduced early and late broods with a foster female onto boreal oligotrophic lakes and monitored subsequent duckling survival. Standardised invertebrate sampling was done concurrently to get a measure of lake-level abundance of aquatic prey, a likely causative agent of putative seasonal difference in duckling survival. Survival data and covariates (duckling age; days) were analysed by an information theoretic approach. There was no effect of treatment (i.e. manipulation of hatching date) on duckling survival, which was higher in 2005 than in 2004. In contrast to observational studies from more seasonal wetlands, our experiment demonstrates that duckling survival on boreal lakes was not affected by a 12-day delay in hatching date. Since we did not find any consistent trends in abundance of aquatic prey, i.e. neither clear peaks nor differences between treatment periods, we hypothesise that moderate climate change has minor effects on resource abundance and hence also on mallard duckling survival in boreal environments.

Experimental evidence for a mismatch between insect emergence and waterfowl hatching under increased spring temperatures

“…On the other hand, ectothermic organisms, like insects, are able to rapidly adjust their development and emergence to the prevailing temperatures, whereas homoeothermic organisms, such as waterfowl, are less likely to evolutionary respond to such changes (Buse et al 1999, Winkler et al 2002. However, some waterfowl, e.g., mallard, are often considered to be relatively flexible in their breeding time (Sjoberg et al 2011, Drever et al 2012. We show here that this is, at least partly, true since both mallard and coot seem to delay their breeding during very cold winters, but, in contrast, show negligible adjustments at temperatures above 78C (Fig.…”

An Overview of Mitigation and Adaptation Needs and Strategies for the Livestock Sector

“…In brief, behavioral traits can be an area for exploring adaptation strategies. Sjöberg et al (2011) [25] examined CC impacts on wild mallard ducks in northern Sweden. They found that moderate CC had minor effects on duckling survival and this could be due to a trait that copes with CC.…”

Early springs and breeding performance in two sympatric duck species with different migration strategies

“…Drever and Clark's () results and ours together suggest that breeding ducks have considerable flexibility to tolerate variation in spring earliness (see also Sjöberg et al . ). This is also consistent with findings by Oja and Pöysä () for Mallard in two study areas in Finland.…”

“…Finally, a decrease in brood size with the length of the interval from ice break‐up to hatching may mirror the general pattern found in birds (including many duck species) of a seasonal decline in reproductive performance (for hypotheses and examples see Sjöberg et al . ). If the timing of breeding does not affect duckling survival, as was experimentally demonstrated in Mallard (Sjöberg et al .…”

“…If the timing of breeding does not affect duckling survival, as was experimentally demonstrated in Mallard (Sjöberg et al . ), it is possible that later hatched broods simply originated from smaller clutches.…”