Animal phenology

Trend in egg-laying dates of the Pied flycatcher across Europe

Note: This map shows the trend in egg-laying dates of the Pied flycatcher across Europe (1980-2004). Dots: weather stations used to calculate changes in local egg-laying dates (derived from temperature data); triangles: location of Pied flycatcher laying date time series.

Data source:

Both, C. and Marvelde, L., 2007. Climate change and timing of avian breeding and migration throughout Europe. Climate Research 35: 93105.

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Past trends

As spring temperatures increased in Europe over the past 30 years, many organisms responded by advancing the timing of their growth and reproduction.
A study in Britain (Crick and Sparks, 1999) analysed 74 258 records for 65 bird species from 1971 to 1995. The study showed significant trends towards earlier (8.8 days on average) laying dates for 20 species (31 %), with only one species laying significantly later. The effects, however, are not necessarily uniform. The predicted egg-laying date for the pied flycatcher (Ficedula hypoleuca), for example, shows significant advancement during the period 1980 to 2004 in western and central Europe, but delays in northern Europe (Figure 1); both are strongly driven by temperature trends (Both and Marvelde, 2007).
Strong and rapid phenological changes have been observed in the high latitudes in response to warming of the region occurring at twice the global average rate (Hoye et al., 2007). The date of snowmelt in northeast Greenland has advanced by an average of 14.6 days since the mid 1990s, resulting in earlier egg-laying dates for birds in the region.

Projections

The future impacts of climate change on animal phenology are poorly understood, but could include increasing trophic mismatch and disturbance to ecosystem functioning. The trend towards warmer springs may continue to induce earlier breeding and migration activity. Unpredictable cold snaps are likely to cause high mortality amongst early movers. Meanwhile, species whose life cycles are calibrated according to day length, and which do not respond so readily to changing temperatures, will not be able to exploit earlier spring resources unless they can adapt.