Migration: Some Do...Some Don't










What ornithologists call 'migration' is actually a continuum of varied behavioral strategies that span from permanent residency to long-distance migration. Although considered a migratory bird, the mourning dove is actually a dimorphic species: one segment of the population migrates - and the other does not. Important factors need to be considered in order to understand the spectrum of why contradicting behaviors can dramatically vary within a species.

While behavior evolves under the influence of natural selection: the process by which in nature only the best adapted physical and instinctive traits enhance the survival of individuals, enabling them to transmit their genes to succeeding generations - it must act on variation: individuals within a species who differ from one another with respect to a particular inheritable genetic trait. These factors are of the highest importance as changing environmental conditions have provided the filter that determines whether individuals within the species inherit true migratory or sedentary habits.

Many aspects of migratory behavior are known to be inherited, but only recently have researchers revealed some of the details. Experiments (Berthold 1996) point to strong genetic control over many of the key components of migratory behavior...if a population is made up of two types of individuals, migrants and non-migrants, the variation must be heritable and have a genetic basis.

The mourning dove's winter range has been gradually moving north year by year, shifting the dynamics of the overall population. It has been hypothesized by dove biologists (Armstrong and Noakes 1983) that successful resident populations could contribute substantially to local recruitment of wintering doves who avoid the hazards of migration and hunting. By remaining year round in the nesting area, resident doves are able to compete more successfully for mates and resources, increasing the length of the breeding season. Furthermore, being the earliest to pair, they are also more likely to select a mate who has also wintered over, genetically reinforcing that behavior in their offspring.

Our resident doves inherently vary from the migrant doves. Unnatural selection imposed by human hunting management schemes could ultimately affect the dynamics of natural selection on Michigan's dove population. The effects of shooting resident birds could, to a greater degree, remove large portions of wintering doves from the overall population. The Atlas of Breeding Birds of Michigan warns that "if the species were hunted here, we would probably lose a large segment of the wintering flock." And we would miss them!

Note: Scientific data, research, studies, etc. were compared and complied from multiple sources. Although some research is cited, this is not the limit to which conclusions were assessed. The Atlas of Breeding Birds of Michigan p 230, Gathering of Angels, Migratory Birds and Their Ecology, Cornell University, Oxford University, MN Star Tribune, Jim Gilbert's Journal Feb 26, 1999, Darwin's Origin of Species, The Beak of the Finch, Ecology and Management of the Mourning Dove, Canadian Field Naturalist Journal 1983 p 434-438.

 

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Page Updated: 05/26/04