Latitudinal variation in arrival and breeding phenology of the pied flycatcher Ficedula hypoleuca using large-scale citizen science data

Pied Flycatcher. Edmund Fellowes

Author(s): Nicolau, P.G., Burgess, M.D., Marques, T.A., Baillie, S.R., Moran, N.J., Leech, D.I. & Johnston, A.

Published: February 2021  

Journal: Journal of Avian Biology

Digital Identifier No. (DOI): 10.1111/jav.02646

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New research uses data from BirdTrack and the Nest Record Scheme to investigate how adaptable breeding Pied Flycatchers are to a changing climate.

Pied Flycatchers are associated with the broadleaf woodlands in the west of Britain where, as a confiding species, they have taken up residence in many bird ringers' nest box schemes. However, like many other long-distance migratory species, British Pied Flycatchers are declining in numbers. New research from BTO has used data from BirdTrack and the Nest Record Scheme to better understand the flexibility of Pied Flycatcher breeding, and how vulnerable this species could therefore be to climate change.

The study used BirdTrack data to assess Pied Flycatchers' arrival dates at their breeding groups across the length and breadth of the country between 2013 and 2016, and then used Nest Record Scheme data to establish the time at which birds initiated laying during the same period. The authors were interested in how much flexibility there was in this interval between arrival and the start of breeding, which would give some indication of this species' capacity to adapt to changing circumstances.

The results showed that birds in the north of the country generally arrived later in the season and started breeding faster compared to birds in the south, which tended to wait longer to initiate breeding. This suggests that birds have the potential to speed up the breeding process when there is an advanced season, for example in the warmer springs predicted to become ever more common under climate change scenarios. There was no relationship between the length of the arrival–breeding interval and clutch size, indicating that birds might not suffer from having less time to spend in preparing for breeding. Breeding onset was also found to be less variable than arrival date, however, suggesting that there is a limit to how much birds could adapt to a changing climate, even if they can adjust their timings to some extent according to varying weather.

The study demonstrates the value of citizen science data as a tool to study species like the Pied Flycatcher, and provides possible future research avenues on how species like this could be helped in forthcoming decades.


The authors thank the many thousands of volunteers who contributed data through BirdTrack, the Nest Record Scheme and Bird Atlas 2007-11. This work was partly funded by the BirdTrack Research Appeal and a legacy from Diana Gay Carr.


Many species have advanced the timing of annual reproductive cycles in response to climatic warming, sometimes leading to asynchrony between trophic levels, with negative population consequences. Long‐distance migratory birds, reliant on short seasonal food pulses for breeding, are considered particularly susceptible to such disjunction because late arrival may preclude optimal timing of egg‐laying. It is unknown whether the relative timing of arrival and egg‐laying is sufficiently plastic, in time and space, to enable an adaptive response when arrival times change relative to local food resources. We used citizen science data, describing pied flycatcher Ficedula hypoleuca arrival and egg‐laying dates, to explore temporal (2013–2016) and spatial (across Great Britain) variation in the phenology of arrival, laying and their difference. To assess the long‐term trend in arrival and laying at a single location, we used data from a long‐term field study. The arrival‐laying interval was consistently shorter in the north, driven by the contrast between spatial variation in arrival date and spatial invariance in laying date. To understand whether a short arrival‐laying interval may have consequences for productivity, we assessed the association between this interval and clutch size. We found no statistically significant correlation between these two variables. To examine long‐term changes in arrival and laying dates, we focussed on a single location in southwestern England. Both dates of first male arrival and first egg laid in a season advanced since 1986, with no evidence of interval shortening. Together, our results demonstrate spatial and annual variation in the arrival‐laying interval, with no detected effect on fecundity. Thus, the interval from arrival to laying is likely dictated by spatially and temporally varying local conditions, suggesting these migrant birds may have the ability to adapt this interval to align with local conditions and mitigate potential mismatch impacts.

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