According to a 2012 study, the combined effects of polar bear predation and parasitism by mosquitoes (itself likely also increasing as a result of higher temperatures) reduced the overall productivity of a thick-billed murre colony in Canada's Hudson Bay by 20 percent in one year, and also increased adult mortality by 20 percent. - See more at: http://www.livescience.com/54619-hungry-polar-bears-decimating-seabird-colonies.html#sthash.lJ5Hbfl4.dpuf