Phenotypic Plasticity and the Snow Goose Population
Q: Asked on Twitter @DeltaWaterfowl: Low rates of gosling growth may suggest density dependence, but snow goose numbers continue to rise. Could this be Phenotypic plasticity?
A: Ultimately, snow goose numbers continue to rise because recruitment still exceeds mortality. As you noted, snow geese have degraded the habitat in their core breeding areas and gosling growth rates in those areas have decreased. However, snow geese have begun expanding their colonies into areas where habitat is in better shape. In these new areas, gosling growth rates are no different than historic estimates and snow goose researchers believe geese breeding there are responsible for much of the population increase. This could certainly be considered "plasticity" as the wiser geese are moving to better breeding habitat. It also seems to indicate some density dependent effects, but we may not see a limit to populations until a greater proportion of the habitat has been degraded.
Another possibility is that low gosling growth rates have not yet reached a level that is detrimental to survival and fecundity. As you mentioned, this could also suggest some phenotypic plasticity (Phenotypic plasticity is the ability of an organism to change physical characteristics (e.g., height, weight, bill size, etc.) in response to changes in their environment). Continuing research by the Hudson Bay Project team should help us answer these and other questions.
Thanks for the thought provoking question!
-Matt Chouinard
Delta Waterfowl Biologist
If you have a question email us at webmaster@deltawaterfowl.org". If it's selected for the web site you will receive a Delta T-Shirt!
Related Links: Despite Conservation Season, Snow Goose Numbers Continue to Grow
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