Bird Species and Climate Change: The Global Status Report - WWF

In Australia:■Arrival dates for 24 species anddeparture dates for 12 species of birdswere analysed using data spanningthe past 40 years. On average, birdsare arriving 3.5 days earlier per decadesince 1960, with half the speciesshowing significantly earlier arrival.These results, reported by Beaumontet al. (2006), “add further evidencethat the modest warming experiencedover the past few decades has alreadyhad significant biological impacts on aglobal scale.”In Antarctica:■East Antarctic seabirds, including Adéliepenguins and six species of petrel, arearriving at their colonies an average of9.1 days later and laying eggs 2.1 dayslater than in the early 1950s. Some birdsare arriving as much as 30 days laterthan in the 1950s. The findings havebeen linked to global climate changewhich has decreased sea ice extent inthis region overall, but caused the seaiceseason to increase by more than 40days due to localised cooling since the1970s. These changes are associatedwith declines in krill, a key prey species.The birds’ delayed arrival and layingdates may reflect the longer feedingtime to build up the energy reservesrequired to breed (Barbraud andWeimerskirch, 2006).3.1.2.2 Autumn departure shiftsBirds’ autumn departure dates alsoappear to be changing, however thiseffect is more difficult to monitor(Crick, 2004). This response to climatechange also appears more variable withsome species advancing and otherspostponing their autumn migration.These differences appear to reflect therelative importance of summer andwinter seasons in completing birds’ lifecycles (Lehikoinen et al., 2004).In Europe:■Birds that winter south of the Saharahave advanced autumn migration anaverage of 2.5 days in the last 40 years,possibly so they can cross the Sahelbefore the seasonal dry period. Bycontrast, migrants wintering north of theSahara have delayed autumn passageby 3.4 days on average over the sameperiod (Jenni and Kery, 2003).In North America:■Of 13 North American passerine birdspecies, six were found to delay theirmigration dates in conjunction withglobal warming (Mills, 2005).3.1.2.3 Failure to migrateIn Europe it appears that climate changeis causing individuals of some birdspecies (which normally migrate) to failto migrate at all.This includes greenfinches, which haveseen a six-fold increase in their winterpopulations in Finland in the last 40years, as fewer individuals migrateto Northern Germany (Lehikoinenet al., 2004).Bird Species and Climate Change: The Global Status Report20Climate Risk