Climate Change Helps to Prepare Geese for Migration

by Anna Alquitela

Greenland white-fronted geese, Anser albifrons flavirostris, spend their winters in Ireland, stage and refuel in Iceland, and breed in Greenland. Because climate change has advanced the spring thaw in Ireland by about 18 days since 1985, these geese have more food to eat and are departing for and arriving in Iceland earlier than previous years. However, climate change has not caused a significant change in the temperatures of Icelandic staging areas and therefore has not caused a significant change in the departure time from Iceland to Greenland, thus the geese are staying in Iceland for a longer period of time than in previous years and arriving at their breeding grounds around the same time as historically known. Fox et al. (2014) used an abdominal profile index (API) as an indicator of fat stores in geese to determine if the amount of stored fat was the cause of advanced departure to Iceland. The authors also considered trends in temperature as indicators of departure time, but found that, because of the migration distances from Ireland to Iceland and Iceland to Greenland, temperatures are “very poor predictors” for departure times; meaning that the geese would not be able to use the temperature in Ireland to predict the temperature in Iceland nor the temperature in Iceland to predict the temperature in Greenland. Compared to previous studies, Fox et al. found that the Greenland white-fronted geese departed Ireland 33 days earlier in 2012 than they did in 1969 and arrived in Iceland 22 days earlier in 2012 than they did in 1997. The authors also note that the mean API at departure from Ireland in 2012 and 2013 increased significantly from previous years. Continue reading

Northeastwards Shifts of Waterbird Species’ Wintering Range in European Flyways

by Cortland Henderson

Several studies of bird range shifts have found northward shifts in wintering distributions. However, these studies have been limited by studying the limits of bird migrations, rather than distributions of whole ranges or populations. Research on European butterfly species has found southern boundary retraction in addition to northern boundary expansion, which calls for further examination of whole bird ranges in European flyways. Using survey data from nine countries over a three-decade period, Lehikoinen et al. (2013) track the centers of gravity of three common waterbird species in Europe to determine spatial shifts of entire ranges. They found that a 3.8 °C increase in early winter temperatures in northeastern sites of the European flyway has been linked to north-eastwards shifts in the entire wintering range of all three waterbird species. In addition to overall shifts, they detected that northern boundaries of bird ranges experienced higher rates of expansion than the rates of retraction of southern boundaries. For the first time at the larger flyway level, wintering distribution changes have been linked to rising temperatures. Continue reading