All the baby birds will starve unless we change our wicked ways.
Climate change leaves birds hungry as chicks hatch too late to eat caterpillars
Earlier springs in UK are throwing animals’ natural rhythms into disarray, resulting in population declines
Josh Gabbatiss Science Correspondent
Monday 23 April 2018 16:15 BST
Warmer springs due to climate change are leaving chicks in UK woodlands hungry, according to new research.
“Previous work has shown a mismatch does lead to population declines,” Dr Karl Evans, one of the study’s authors at the University of Sheffield, told The Independent.
Dr Malcolm Burgess, a bird researcher at the University of Exeter and the RSPB who led the research, added: “Forests have a short peak in caterpillar abundance, and some forest birds time their breeding so this coincides with the time when their chicks are hungry.
“With spring coming earlier due to climate change, leaves and caterpillars emerge earlier and birds need to breed earlier to avoid being mismatched. We found that the earlier the spring, the less able birds are to do this.”
“Birds shift the timing of breeding, and they tend to breed earlier in springs that are warmer – but the manner in which they are shifting isn’t sufficiently rapid, that’s the theory,” said Dr Evans.
“People are starting to look at whether there’s capacity for evolutionary change to improve their ability to match, but the evidence is very mixed at the moment.”
The abstract of the study;
Tritrophic phenological match–mismatch in space and time
Malcolm D. Burgess, Ken W. Smith, Karl L. Evans, Dave Leech, James W. Pearce-Higgins, Claire J. Branston, Kevin Briggs, John R. Clark, Chris R. du Feu, Kate Lewthwaite, Ruedi G. Nager, Ben C. Sheldon, Jeremy A. Smith, Robin C. Whytock, Stephen G. Willis & Albert B. Phillimore
Increasing temperatures associated with climate change may generate phenological mismatches that disrupt previously synchronous trophic interactions. Most work on mismatch has focused on temporal trends, whereas spatial variation in the degree of trophic synchrony has largely been neglected, even though the degree to which mismatch varies in space has implications for meso-scale population dynamics and evolution. Here we quantify latitudinal trends in phenological mismatch, using phenological data on an oak–caterpillar–bird system from across the UK. Increasing latitude delays phenology of all species, but more so for oak, resulting in a shorter interval between leaf emergence and peak caterpillar biomass at northern locations. Asynchrony found between peak caterpillar biomass and peak nestling demand of blue tits, great tits and pied flycatchers increases in earlier (warm) springs. There is no evidence of spatial variation in the timing of peak nestling demand relative to peak caterpillar biomass for any species. Phenological mismatch alone is thus unlikely to explain spatial variation in population trends. Given projections of continued spring warming, we predict that temperate forest birds will become increasingly mismatched with peak caterpillar timing. Latitudinal invariance in the direction of mismatch may act as a double-edged sword that presents no opportunities for spatial buffering from the effects of mismatch on population size, but generates spatially consistent directional selection on timing, which could facilitate rapid evolutionary change.
Read more (paywalled): https://www.nature.com/articles/s41559-018-0543-1
Sadly the full study is paywalled, but in my opinion this study doesn’t pass the smell test.
Suggesting that birds might not have the capacity to adapt, when they clearly managed to adapt to far worse in the comparatively recent past, in my opinion is ridiculous.
Just under 13,000 years ago the world experienced the Younger Dryas. The Younger Dryas was a 1200 year catastrophic plunge in global temperature which struck with full force in as little as a few months. In the words of one researcher, “It would be like taking Ireland today and moving it up to Svalbard“.
Unusual spring weather likely does put pressure on baby birds. Britain frequently has late Spring cold snaps which probably causes harm to vulnerable fledglings. But the mild warming we have experienced over the last few centuries does not come anywhere close to the disruption radical climate shifts of the past like the Younger Dryas must have caused – climate shifts which most bird species obviously survived.