The impact of climate change on the phenology of short- and long-distance migratory birds

Abstract

Quickly changing temperatures due to climate change are expected to have devastating consequences on the migratory bird populations around the globe. However, surprisingly, several studies have demonstrated that some species may be able to keep up with the unusually rapid changing temperatures that we are experiencing, as a variety of species in these studies have shown changes in their migratory behavior in response to these changing temperatures. This thesis aims to determine how climate change will affect the migratory behavior in birds and which bird species will be more resilient to these changes. It was hypothesized that short-distance migrants would be more resilient and better able to adapt to climate change than long-distance migrants, and that short- distance migrants would shorten their migratory journey or become residents on their breeding grounds. Two case studies were investigated to determine whether this hypothesis was valid: case study #1 examined the shifts in bird migration timing of long- and short-distance migrants, and case study #2 explored the selection for lower migratory activity and residency in previously migratory bird populations. It was found that short- and long-distance migrants are both responding significantly to the changing temperatures and are adjusting their migration times accordingly. In short-distance migrant populations, it was found that the increased global temperatures are currently favouring birds that are expressing reduced migratory activity. These results suggest that phenotypic plasticity and/or microevolution are at play. It has been concluded that it is still more likely that short-distance migrants are more resilient to climate change than long-distance migrants in the long-run because they show more genetic variability in their phenotypic responses, which means that they have a greater evolutionary potential than long-distance migrants.