Cuckoos tune spring migration to climate change but still may suffer from a phenological mismatch 

Climate change and increasing spring temperatures caused cuckoos to have advanced their spring arrival dates over the last 36 years. However, cuckoo arrivals advanced less than those of their hosts and also less than the spring emergence date of their prey over decades. All of this suggests that cuckoos may potentially suffer from increasing arrival mismatch with their hosts and prey, as international team of researchers from the TUM School of Life Sciences and Institute for Advanced Study of Technical University of Munich (Germany), Faculty of Environmental Sciences of Czech University of Life Sciences Prague (Czechia), Institute of Zoology of Poznań University of Life Sciences (Poland) and Tatarstan Academy of Sciences (Russia) have found in a recent study. The research results have been published in the Royal Society Open Science journal.

“Matching the timing of spring arrival to the breeding grounds with both hosts and prey is crucial for migratory brood parasites such as cuckoos. However, we found that climate change may disrupt co-fluctuation in the phenology of important life stages between cuckoos, their hosts, and prey,” says Peter Mikula, the main author of the study.

Mikula and his colleagues found that the common cuckoo (Cuculus canorus) which spend winter in Africa generally arrived on breeding grounds in Tatarstan, Russia, earlier than the oriental cuckoo (C. optatus), wintering in southeast Asia and Australia. Warmer spring temperatures caused both cuckoos and their hosts to arrive on their breeding grounds earlier over the years. Moreover, the main prey of these cuckoos, hairy caterpillars and large beetles, emerged earlier in spring over decades. However, cuckoos’ arrival advancement was generally smaller than that of their hosts and prey.

“Over years, we have developed a nice collaboration with local researchers and citizen scientists who collected long-term data on the first arrival date of two migratory cuckoo species and their host species, as well as their prey emergence date between 1988 and 2023 in Tatarstan, Russia. Without their help, this study won’t be possible,“ explains Piotr Tryjanowski, Hans Fischer Senior Fellow of the TUM Institute for Advanced Study, who supervised the study.

Cuckoos are often host and prey specialists. Hence, due to phenological asynchrony, cuckoos may miss optimal timing of parasitizing their hosts and peak in their prey availability. Temporal and spatial mismatch between cuckoos and their hosts may cause host switch in cuckoos and change parasitism rates in host populations. Cuckoos as prey specialists may also potentially affect their population dynamics. Both cuckoo species have declining populations and potentially increasing phenological asynchrony may partially be responsible for these declines.

“Previous studies on climate-driven shifts in spring arrival and potential phenological mismatch focused only on a single cuckoo species, particularly in Europe, and did not consider spring phenology of cuckoo prey. Our results provide some evidence that increasing phenological asynchrony in arrival date between cuckoos and their hosts is also present in common cuckoo populations outside Europe and also in other migratory cuckoo species.” Mikula said. “Moreover, climate change may also disrupt trophic interactions between cuckoos and their prey.”

royalsocietypublishing.org/doi/10.1098/rsos.231691

Reference

Mikula P., Askeyev O. V., Askeyev A. O., Askeyev I. V., Morelli F., Menzel A. & Tryjanowski P. (2024). Climate change is associated with asynchrony in arrival between two sympatric cuckoos and both host arrival and prey emergence. Royal Society Open Science, doi: 10.1098/rsos.231691.