1stalker
01-15-2013, 03:59 PM
I came across an interesting read, and was hoping for some feedback from the forum followers....
We have all seen the effects on the Mule deer over the last couple years.
Subject: Effects of White-Tailed deer on Mule Deer
By Val Geist
Dr. Susan Lingle carried out in Calgary experimental studies in captivity as well - over decades - observation on free-living sympatric populations of mule deer and whitetails in southern Alberta. Her Masters and subsequent PhD degree from Cambridge were based on her excellent work there. She is currently a professor in biology at the University of Winnipeg.
Thanks to her work, we can be quite confident about how whitetails impact mule deer. And I am the bearer of bad tidings: the demise of mule deer in the presence of whitetails is - unfortunately - a consequence of mismanagement.
Here is the story.
In un-hunted populations, mule deer and white-tailed deer co-exist without noticeable problem. Mule deer are totally dominant over whitetails. White-tailed deer of both sexes are attracted to mule deer during the rut, but not vice versa. That is even true when estrus white-tailed does avidly court large mule deer bucks. Hybridization, when it does take place, is almost exclusively by mule deer does being bred by white-tailed bucks.
However, in unhunted population such is minimal as long as eager white-tailed bucks meet a large mule deer buck guarding an estrus doe. The large mule deer buck is totally dominant over all white-tailed bucks. The fate of the hybrid is early mortality due to predation as the hybrid has neither the escape strategies nor tactics of the father or the mother. This Susan Lingle demonstrated experimentally.
Hybrids run slower than either parent, hit obstacles while jumping, and do neither attack nor flee from a predator. In captivity, protected by humans, the hybrids grow into large deer and the females into highly fertile mothers that raise big babies.
That's not what happens in the wild state with abundant predators. The reproduction of a mule deer female bred by a white-tailed buck is a net loss to the mule deer population. One way hybridization accelerates and can be catastrophic where hunting (a) removes the large mule deer males, and (b) the disturbances drive mule deer does into cover.
Here they are in the habitat of white-tailed deer. Large white-tailed bucks displace small guarding mule deer bucks and breed the estrus mule deer females. The reproduction of mule deer is thereby severely impaired and their number declines.
However, there are pockets of mule deer that survive in a sea of whitetails. How come? Such pockets of surviving mule deer are found in prairie sand dune country. The reasons for mule deer survival are perfectly logical in view of their breeding biology. When a white-tailed buck picks up a female mule deer, the female mule deer - escapes by stotting straight-up the slopes of the hills. The white-tailed buck, with his fast rotary gallop cannot follow. He can at best ascend at a diagonal.
Secondly, in the sand hill country with its sparse vegetation, any fleeing mule deer doe is at once spotted by a large mule deer buck as such occupy good lookouts (there is a reason why the eyes of prairie mule deer almost as large as those of pronghorns). In short, in sand dune country the manner in which the mule deer doe escapes combined with the visibility favors here being bred by a large mule deer buck.
Moreover, where mule deer and whitetails coexist mule deer does attack coyotes that approach mule deer or white-tailed fawns. Whitetails do not reciprocate the favor. That's another of Susan Lingles significant finds.
The best way to exterminate mule deer and insure that whitetails replace them is to kill as many mature mule deer bucks as possible.
Then one-way hybridization will take care of the mule deer.
The first measure needed to secure the existence of mule deer when whitetails invade is to protect a large contingent of mature, older mule deer bucks.
Secondly, there must be simultaneously a very liberal hunting seasons on white-tailed deer. That may be a difficult management strategy to implement as it would require a severe cutting back on mule deer hunting, and dispensing the limited buck licenses via lottery.
I am well aware of that difficulty! However, look where mule deer are holding their own against whitetails.
Another little point: whitetails are non competitors. To see real food competitors in action, study Eurasian deer. Wherever whitetails faced Sika deer, fallow deer, red deer, or axis deer they vanished. One reason why in Europe whitetails hold themselves only in Finland on agricultural land is the absence of roe deer, fallow deer or red deer.
The above is not new and was worked out in the 1980's, see also Lingle's award winning work and my chapters on WT and mule deer in my 1998 Deer of the World.
Cheers, Val Geist
We have all seen the effects on the Mule deer over the last couple years.
Subject: Effects of White-Tailed deer on Mule Deer
By Val Geist
Dr. Susan Lingle carried out in Calgary experimental studies in captivity as well - over decades - observation on free-living sympatric populations of mule deer and whitetails in southern Alberta. Her Masters and subsequent PhD degree from Cambridge were based on her excellent work there. She is currently a professor in biology at the University of Winnipeg.
Thanks to her work, we can be quite confident about how whitetails impact mule deer. And I am the bearer of bad tidings: the demise of mule deer in the presence of whitetails is - unfortunately - a consequence of mismanagement.
Here is the story.
In un-hunted populations, mule deer and white-tailed deer co-exist without noticeable problem. Mule deer are totally dominant over whitetails. White-tailed deer of both sexes are attracted to mule deer during the rut, but not vice versa. That is even true when estrus white-tailed does avidly court large mule deer bucks. Hybridization, when it does take place, is almost exclusively by mule deer does being bred by white-tailed bucks.
However, in unhunted population such is minimal as long as eager white-tailed bucks meet a large mule deer buck guarding an estrus doe. The large mule deer buck is totally dominant over all white-tailed bucks. The fate of the hybrid is early mortality due to predation as the hybrid has neither the escape strategies nor tactics of the father or the mother. This Susan Lingle demonstrated experimentally.
Hybrids run slower than either parent, hit obstacles while jumping, and do neither attack nor flee from a predator. In captivity, protected by humans, the hybrids grow into large deer and the females into highly fertile mothers that raise big babies.
That's not what happens in the wild state with abundant predators. The reproduction of a mule deer female bred by a white-tailed buck is a net loss to the mule deer population. One way hybridization accelerates and can be catastrophic where hunting (a) removes the large mule deer males, and (b) the disturbances drive mule deer does into cover.
Here they are in the habitat of white-tailed deer. Large white-tailed bucks displace small guarding mule deer bucks and breed the estrus mule deer females. The reproduction of mule deer is thereby severely impaired and their number declines.
However, there are pockets of mule deer that survive in a sea of whitetails. How come? Such pockets of surviving mule deer are found in prairie sand dune country. The reasons for mule deer survival are perfectly logical in view of their breeding biology. When a white-tailed buck picks up a female mule deer, the female mule deer - escapes by stotting straight-up the slopes of the hills. The white-tailed buck, with his fast rotary gallop cannot follow. He can at best ascend at a diagonal.
Secondly, in the sand hill country with its sparse vegetation, any fleeing mule deer doe is at once spotted by a large mule deer buck as such occupy good lookouts (there is a reason why the eyes of prairie mule deer almost as large as those of pronghorns). In short, in sand dune country the manner in which the mule deer doe escapes combined with the visibility favors here being bred by a large mule deer buck.
Moreover, where mule deer and whitetails coexist mule deer does attack coyotes that approach mule deer or white-tailed fawns. Whitetails do not reciprocate the favor. That's another of Susan Lingles significant finds.
The best way to exterminate mule deer and insure that whitetails replace them is to kill as many mature mule deer bucks as possible.
Then one-way hybridization will take care of the mule deer.
The first measure needed to secure the existence of mule deer when whitetails invade is to protect a large contingent of mature, older mule deer bucks.
Secondly, there must be simultaneously a very liberal hunting seasons on white-tailed deer. That may be a difficult management strategy to implement as it would require a severe cutting back on mule deer hunting, and dispensing the limited buck licenses via lottery.
I am well aware of that difficulty! However, look where mule deer are holding their own against whitetails.
Another little point: whitetails are non competitors. To see real food competitors in action, study Eurasian deer. Wherever whitetails faced Sika deer, fallow deer, red deer, or axis deer they vanished. One reason why in Europe whitetails hold themselves only in Finland on agricultural land is the absence of roe deer, fallow deer or red deer.
The above is not new and was worked out in the 1980's, see also Lingle's award winning work and my chapters on WT and mule deer in my 1998 Deer of the World.
Cheers, Val Geist