Barnacle geese are adjusting to rising temperatures in Norway, having migrated 250km further north from their traditional staging areas. This has been in response to earlier spring temperatures melting the ice at their usual stopping points along their journey from the UK to their breeding grounds on Svalbard. The migratory change is further encouraged by sufficient food supplies further north as the migration patterns of marine life also become affected by rising ocean temperatures, causing Atlantic species of cod, herring and mackerel to move northwards.
Notably, it’s younger geese that are altering the migration routes. This is a possible result of their inclination to explore, however, due to barnacle geese’s socially-learned behaviour patterns, older geese are following their younger counterparts as they travel. The population of barnacle geese is now spreading across a far wider range, which Dr Thomas Oudman of the School of Biology at the University of St Andrews, author of a new study into the geese, notes is ‘like spreading your chances when gambling’ - referring to the geese’s survival options. Oudman identifies this ‘innovativeness’ in adapting patterns of migration as a possible reason for the rapid growth rate of barnacle geese, numbers of which have doubled in the last 25 years. This is not, however the case for other species whose ‘social learning’ isn’t as innate or rapid as that of geese.
In the natural world, changing growth rates or migratory patterns will have a knock-on effect for other species through alterations to the food chain and competition for differing resources. Oudman notes that barnacle geese are thriving in their newly colonised environment and are ‘pushing out pink-footed geese’, therefore gaining a larger supply of the agricultural land available to feed on. He also observes that changes in food availability in the staging areas influence reproductive success, another factor contributing to the geese’s population increase.
The barnacle geese are, however, now under increasing threat from polar bears hunting for the birds’ eggs on the coast of Svalbard. Like the geese, polar bears are also learning alternative habits to adjust to climate change as the ice where they would otherwise be hunting seals is melting. On average, spring is advancing by half a day each year, meaning ice is breaking up and melting earlier and earlier, forcing polar bears to come ashore during nesting time for the geese.
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