Common Buzzards do Better with Colder Environments and Greater Snowfall

by Hilary Bruegl

In Eastern Westfalia, Germany, the varying North Atlantic Oscillation (NAO), which characterizes atmospheric pressure in areas surrounding the North Atlantic Ocean, affects the habitat specifications of the Common Buzzard Buteo buteo, causing a range of survival factors key to this predator’s life cycle to adjust accordingly. Jonker, et al. (2014) discuss the possible factors involved in population survival rates and overall population size in four study locations including the Teutoburger forest, Kiefernheide, Ravensberger Land, and Lower-Saxony. These locations vary in humidity, foliage type, and presence of predators. The authors deduced that time, NAO, spring rainfall, availability of prey, physical appearance or morph, and birth year were the variables most responsible for survival within a buzzard population. A decrease NAO was found to be the overarching variable that ultimately affected prey availability and rainfall, and correlated closest with an increase in buzzard survival. Continue reading

Red Fox Populations Encroach on Arctic Fox Ranges due to Warmer Temperatures

by Hilary Bruegl

In the nineteenth century Arctic tundra of Finnmark, Norway, the Arctic fox population declined to near extinction and have been recovering minimally despite strict protection. Hamel et al. (2013) investigated potential factors involved in suppressing healthy recolonization of prior territories, including encroaching red fox populations and variation in prey availability. By baiting and periodically photographing the area, the authors found red foxes to be the most important influence on the Arctic fox population in northeast Norway. Not only are red foxes more comfortable in the warming temperatures of the tundra, but there has also been a significant reduction in fox hunting, allowing the red fox population to flourish. Rodent population fluctuations were first documented alongside fox populations as a limiting factor of population growth; however, they had fewer effects than either land cover changes or red fox infiltration. Continue reading

Reduced Ice and Polar Bears in Beaufort and Chukchi Seas

by Hilary Bruegl

Polar bears in the Arctic rely on sea ice as a means of locating and hunting for seals, their primary food source. Because populations of polar bears can be quite variable, their responses to climate change also depend on reproductive and hunting strategies employed by each population, especially when faced with declining sea ice. The Chukchi Sea (CS) population of polar bears was found to have greater body size and overall condition in a period of four years between 2008–2011 as compared to previous CS population data from 1986–1994 as well as compared to the 2008–2011 Beaufort Sea (SB) population of polar bears (Rode et al. 2014). The SB population of polar bears has been exposed to declining sea ice conditions for longer periods of time than the CS population, allowing for compounding effects over generations, which may account for some Continue reading

Emperor Penguin Colonies Move from Sea Ice to Antarctic Ice Shelves for Breeding when Climate Temperatures Delay Sea Ice Formation

Emperor penguin colonies characteristically use Antarctic sea ice for both breeding and foraging. In recent years, emperor penguins have moved onto ice shelves, which are composed of glacial ice and characterized by tall cliffs that are often thought too steep for this less-agile penguin species. Ice shelves are much more weather resistant and structurally reliable than sea ice, which is more weather dependent, seasonal and much thinner as it comprises the top layer of sea water during winter months. Fretwell et al. (2014) observed four colonies found breeding on ice shelves, and they recorded movement and foraging habits using satellite imagery during typical winter months over five seasons from 2008–2012. The penguins were generally loyal to breeding locations and when relocating, they relocated as a colony. Of the ice-shelf locations, those on which emperor penguins permanently resided over the course of the study were warmer in temperature, and the surrounding sea ice formed later into the breeding season after the colonies had already begun to use ice shelves. Submitted by Hilary Bruegl

Fretwell, P. T., Trathan, P. N., Wienecke, B., Kooyman, G. L., 2014. Emperor Penguins Breeding on Iceshelves. PloS one, doi:10.1371/journal.pone/0085285. Continue reading