Data on the spring arrival dates of 23 species of migrants in Sand Martin, Blackcap and Sedge Warbler showed a significant trend towards earlier arrival over the period, while Tree Pipit, Cuckoo, Whinchat, Whitethroat and Garden Warbler showed a significant trend towards later arrival. Fifteen species arrived noticeably earlier in the 1940s, a period of warm springs, while several species showed earlier arrivals in the 1980s. A number of species showed later arrival dates in the 1960s and 1970s, when April temperatures were colder than average. Several species showed significant correlations between arrival date and temperature. Arrival dates of the earliest species were much more variable than those arriving later, while species arriving in the second half of April showed a generally synchronous arrival. The results are discussed in the context of global warming.

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We examine the first arrival and last departure dates of migrant bird species from, respectively, six and three English area bird reports. Of all 145 bird series, 50% demonstrated significantly earlier arrival in recent years, with the average advance over all species being 0.25 days/year or 12 days earlier over 50 years. Thirty percent of 67 series demonstrated significantly later departure, with the average species delay being 0.16 days/ year or eight days later over 50 years. There was greater consistency between species in trends in first arrival than in last departure, with species such as sand martin Riparia riparia significantly earlier at all six sites while, for example, spotted flycatcher Muscicapa striata showed no significant change in arrival at all sites. Significant negative correlations between arrival dates and English temperatures were found for 26% of all series, but temperature effects on departures were less clear. We provide some evidence that trends in arrival dates may be masked by population declines in birds. Since migrant bird populations are in decline generally, this may suggest that the real advance in arrival dates may be greater than that reported here.

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