A University of Victoria study could offer hope for those who want to see the regionB次元官网网址檚 deer population controlled without resorting to a cull.
Predators lower the population of their prey, not just by killing them, but by scaring them as well.
ItB次元官网网址檚 a conclusion made by a team of researchers who believe behavioural research collected on song sparrows in the Gulf Islands could be applied to predator-prey interactions of all kinds and used to manage their populations.
B次元官网网址淭he fear of falling victim to a predator can also have significant effects and affect the number of babies you have,B次元官网网址� said Michael Clinchy, adjunct professor at the UVic and co-author of the study. B次元官网网址淭his can be as important as direct killing in reducing prey numbers.B次元官网网址�
Over the past 10 summers, Clinchy, along with University of Western Ontario biologist Liana Zanette and UVic grad students, used electric fencing and fish-netting to fully protect sparrow nests from natural predators such as owls and raccoons on Portland Island and surrounding Gulf Islands. Through speakers hung in surrounding trees, one group of birds were subjected to recorded predator calls and sounds, while sounds of non-predatory animals such as geese played for a second group of song sparrows.
Clinchy and Zanette observed the birds via video and learned those exposed to predator sounds produced 40 per cent less offspring than the control group. These birds also spent more time guarding their nests and less time feeding their young, which also reduced their numbers.
B次元官网网址淚tB次元官网网址檚 the first time in any study of wild bird or mammal that fear alone has been shown to unambiguously affect birth and survival and thus the individuals in wildlife interactions,B次元官网网址� Clinchy said. B次元官网网址淏asically we think that this kind of fear effect is going to be pervasive on wildlife.B次元官网网址�
Clinchy links his work to the management of elk populations in the American Yellowstone National Park and doesnB次元官网网址檛 overrule the possibility of controlling deer in Greater Victoria using the same principal. When wolves were reintroduced to the park in the mid-90s, the elk population decreased by 50 per cent B次元官网网址� a reduction far greater than what the wolves were capable of killing, Clinchy said.
B次元官网网址淚tB次元官网网址檚 the fear itself thatB次元官网网址檚 really responsible,B次元官网网址� he said. B次元官网网址淚f you can simulate that, you could have effects in reducing the deer population.B次元官网网址�
The study, Perceived Predation Risk Reduces the Number of Offspring Songbirds Produce per Year, was published in the December issue of Science magazine.
nnorth@saanichnews.com
