The disproportionate effect of global warming on the arrival dates of short‐distance migratory birds in North America

Abstract

Recent studies have shown that, in response to global climate change, diverse avian taxa are now nesting measurably earlier (< 10 days) in both the United States and Britain. Similarly, several studies on European birds have now demonstrated that a variety of species (although not all) are arriving increasingly early. However, surprisingly, widespread changes in North American migrant phenology have not been demonstrated. It is hypothesized that short‐distance migrants (birds that winter in the southern United States) may be quicker to adapt to climate change than long‐distance migrants (birds that winter south of the United States), as short‐distance migrants can respond to meteorological cues indicating weather conditions to the north whereas long‐distance migrants must rely on photoperiod. This study examined the first arrival dates of 103 migrant birds in New York and Massachusetts and found that, on average, all migrants arrived significantly earlier during the period 1951–1993 than the period 1903–1950. From 1951–1993 birds wintering in the southern United States arrived on average 13 days earlier while birds wintering in South America arrived 4 days earlier. Although a change in observer effort cannot be quantified and may be a source of bias, a comparison of the numbers of reporting observers during the 1930s and the 1980s revealed no significant difference. These results are consistent with those expected under a scenario of global warming.

Spring Bird Migration Phenology in Eilat, Israel

“…In several species we found a signifi cant correlation between initial capture dates in the spring and in the calendar years ( A comparison of mean data regarding initial capture dates during the two consecutive decades indicated that all 34 species arrived on average three days earlier from 1984-1993than from 1994-2003. However, the diff erence is not statistically signifi cant (Mann-Whitney U Test, U= 563, Z= 0.184, p = 0.854).…”

“…Some of these can be attributed to the infl uence of global warming on avian spring migration, as shown by several studies (Bairlein and Winkel 2001;Sokolov 2001;Sparks et al 2001;Hüppop and Hüppop 2003;Butler 2003). Only the Orphean Warbler showed a strong positive correlation of initial capture with the calendar year, whereas the Barred Warbler and Grey Flycatcher displayed insignifi cant trends.…”

Sources of Measurement Error, Misclassification Error, and Bias in Auditory Avian Point Count Data

“…Temporal trends in factors such as average singing rates, that influence availability during a count, can also impart trends in count data unrelated to the true abundance. For example, there is increasing evidence that birds are breeding earlier now than in the past, presumably due to global warming (Butler 2003). Climatic trends that impart trends in the average singing rates of birds will bias abundance estimates over time unless analyses account for the temporal trends in detection probabilities.…”

What prevents phenological adjustment to climate change in migrant bird species? Evidence against the “arrival constraint” hypothesis

“…Moreover, FADs correlate positively with mean arrival date for species where the latter can be calculated Tøttrup et al 2006) and have been widely used to determine temporal change in migration (e.g. Sparks, 1999;Both and Visser, 2001;Butler, 2003;Cotton 2003;Sparks et al 2007). Analysis of FADs is particularly robust for analysing temporal change for the same population 72 (as here) (Tryjanowski et al 2005).…”