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A Phenological Mismatch Between a Wild Bird and Its Food Source
Reed, T.E., Grotan, V., Jenouvrier, S., Saether, B.-E. and Visser, M.E. 2013. Population growth in a wild bird is buffered against phonological mismatch. Science 340: 488-491.

The authors write that "climate change can disrupt preexisting synchrony between interacting species in the seasonal timing (i.e., phenology) of their life-history events," and they note that a case in point concerns great tits (Parus major) of the Netherlands in relation to the phenology of their caterpillar food supply, since "this part of Western Europe has experienced substantial spring warming in recent decades related to global climate change (Visser et al., 1998)," and because "the caterpillar food peak has advanced in response to rising spring temperatures at more than twice the rate of great tit laying dates (Visser et al., 1998; Visser et al., 2006)."

What was done
Throughout a period of almost four decades, during which time late spring temperatures increased by 3.7°C, Reed et al. tested whether the population growth of great tits of the Netherlands was negatively affected by the succession of warmer springs that "generated a mismatch between the annual breeding time and the seasonal food peak."

What was learned
The five researchers report that "there were no statistically significant linear nor quadratic effects of population mismatch on population growth," implying that "mistiming did not depress mean fitness" and that "fitness losses associated with mismatch are counteracted by fitness gains due to relaxed competition."

What it means
In the concluding sentence of their paper's abstract, Reed et al. state that their findings imply that "natural populations may be able to tolerate considerable maladaptation driven by shifting climatic conditions without undergoing immediate declines." And as they state in the concluding sentence of the body of their paper, "our results imply that considerable directional selection might be demographically tolerable on decadal time scales without immediate population declines, effectively buying time for microevolution to restore adaptation."

Visser, M.E., Holleman, L.J.M. and Gienapp, P. 2006. Shifts in caterpillar biomass phenology due to climate change and its impact on the breeding biology of an insectivorous bird. Oecologia 147: 164-172.

Visser, M.E., van Noordwijk, A.J., Tinbergen, J.M. and Lessells, C.M. Warmer springs lead to mistimed reproduction in great tits (Parus major). 1998. Proceedings of the Royal Society London Series B - Biological Sciences 265: 1867-1870.

Reviewed 4 September 2013