Northern Fulmars and Climate Change

The effects of climate change on northern fulmars have not been clearly established, but several clues to links between climate and northern fulmar dynamics have been investigated and are presented here.

There has been a series of studies on the relationship between WNAO and population dynamics of northern fulmars on an island called Eynhallow in Orkney, Scotland. The North Atlantic Oscillation (NAO) is a large-scale climate pattern, reflecting pressure differences between northern and southern Europe (Osborn 2006). In northern Europe winters with a negative NAO index are usually cold and dry, while winters with a positive NAO index are usually mild, wet and stormy (Osborn 2006). Global climate change is thought to result in changes in NAO patterns (Osborn 2006). The Winter NAO (WNAO) index has been found to be negatively related to survival (Grosbois & Thompson 2005) and breeding success in the following summer (Lewis et al. 2009; Thompson & Ollason 2001) in the northern fulmar population on Eynhallow. The WNAO index lagged by one year was found to have a negative relationship with breeding success in Lewis et al. (2009) but not in Thompson and Ollason (2001). The negative effect of the WNAO on breeding success have been hypothesised to be either due to a reduction in prey availability both in winter and during the breeding season or due to unfavourable changes in foraging conditions (Lewis et al. 2009; Thompson & Ollason 2001). The effect of the lagged WNAO may represent the time it takes for negative effects on lower trophic levels to filter up to the level of northern fulmar prey (Lewis et al. 2009). Lewis et al. (2009) identified an interaction between past breeding success and the WNAO, so that pairs with high past breeding success could maintain a high reproductive output even as the WNAO index increased. However, my bachelor project (which you can read more about here) did not find strong evidence for an effect of WNAO on breeding success and it might be that the previously established relationship was mainly a result of correlated trends in WNAO and breeding success on the island.

On the other hand, studies of more northern colonies have found that northern fulmars may actually benefit from climate change, at least in the short-term (Gaston et al. 2005). This is because warmer temperatures lead to a reduction in sea ice around breeding colonies, which means that northern fulmar parents don't have to travel as far to access food, and can therefore provide better care for their chicks, who as a result have a higher survival rate.

Mallory and Forbes (2007) observed variations in breeding phenology between southern and northern colonies of breeding fulmars, where birds in northern colonies arrived later, took a much longer pre-laying exodus and spent less time at the colony before egg-laying. If these differences are adaptive adjustments to local climatic conditions, it is unclear how well the breeding phenology fulmars can respond to changes in local climate and what effects this may have on reproductive success and population trends. However, there seems to be no indication of a northward shift as a response to climate change, with southern colonies even increasing in size (Kerbiriou 2012).

To sum up, the effect of climate change on northern fulmars is far from clear, in spite of several colonies being subject to long-term monitoring. This is not surprising, considering the complexity of external factors influencing population dynamics, including food availability, competition, predation, pollution and climate, as well as interactions between all these factors. Continued efforts are needed to fully assess how environmental changes resulting from human activities will influence the fate of this species.

References:

Gaston, A.J., Gilchirst, H.G. and Mallory, M.L., 2005. Variation in ice conditions has strong effects on the breeding of marine birds at Prince Leopold Island, Nunavut. Ecography 28: 331-344.

Grosbois, V. & Thompson, P.M., 2005. North Atlantic climate variation influences survival in adult fulmars. Oikos 109: 273-290.

Kerbiriou, C., LeViol, I., Bonnet, X. and Robert, A., 2012. DYnamics of a northern fulmar (Fulmarus glacialis) population and the southern limit of its range in Europe. Population Ecology 54: 295-304.

Lewis, S., Elston, D.A., Daunt, F., Cheney, B. & Thompson, P.M. (2009). Effects of extrinsic and intrinsic factors on breeding success in a long lived seabird. Oikos 118: 521-528.

Mallory, M.L. and Forbes, M.R., 2007. Does sea ice constrain the breeding schedules of high Arctic Northern Fulmars? Condor 109: 894-906.

Osborn, T.J., 2006. Recent variations in the winter North Atlantic Oscillation. Weather 61: 353-355.

Thompson, P.M. and Ollason, J.C., 2001. Lagged effects of ocean climate change on fulmar population dynamics. Nature 413: 417-420.