Study: Mule Deer, Predators, & Drought

[KFhunter]

These aren't good success numbers,  also I tossed up a cougar graph for district 1 just for giggles.

[DOUBLELUNG]

As a former big game biologist, I think the article is poorly written.  History has taught us that when predator populations in the west were nearly exterminated, mainly by government poisoning campaigns, game populations exploded - even though the range was grazed far more heavily than it is today.  Essentially, livestock removed so much of the low annual vegetation that it mimicked the habitat effect of decades of drought.  I would bet dollars to donuts, those fawns were fairly small, and died in droves during tough winters - but otherwise survived, and mule deer were far more productive - not in terms of birth rates, but survival.  The reason being, except for severe winters, in the northern half of the western US, nearly every fawn that dies, succumbs to predation.  Predation rates skyrocket when hiding cover is poor and fawns grow slowly due to limited forage - but that is only the case if there are predators.  In a predator-free landscape, survival is going to be high (except winterkills).  That was essentially the case from the early 1900s, to the mid 1970s (Nixon's Executive Order banned the use of 1080 to poison predators in 1972, effects of the ban were seen by the late 70s.  Reagan reversed Nixon's ban in 1982, but EPA continues to impose a ban.)

Since 21st Century America is not going to allow the re-extermination of predator populations with poison (hell, we'd be lucky to get back body-gripping traps!), managing game populations in the presence of predators - especially robust predator populations like we've got - habitat quality becomes crucial for perpetuation of game populations - young need security to hide from predators, and high quantities of high quality forage to get as big as possible as fast as possible, both to minimize the period when they are extremely vulnerable, and also to have enough energy during mild to average winters to deal with the added energetic burden of being hunted.

Even when the herd size is being maintained, there is a much smaller surplus that can be taken by hunters because so many of the animals excess to recruitment needs feed predators rather than being shot by hunters. 

As for density-dependence, that really only is a factor when predator populations are an insignificant cause of deer mortality - and then, in that case, densities must rise to extremely high levels before the deer damage their habitat to the point of die-off.  This is also much more likely to occur in southwestern, rather than northwestern US with mule deer, as there is so much less annual forage production under normal conditions - read up on the Kaibab Plateau mule deer for the textbook example.  Even then, it is not until adult does are STARVING to death that density dependence kicks in.

Even without predators, we hit social carrying capacity here in Washington long before the habitat becomes limiting - severe winter the sole exception.  What is social carrying capacity?  That is when people are complaining about too many deer vehicle collisions, ag growers are complaining about crop damage, the people who just built a house on the winter range lose $10,000 worth of arbor vitae and roses, timber companies are complaining about damage to seedlings, etc. - we crank out the doe opportunities long before the population is limited by habitat - severe winter the sole exception.

[KFhunter]

As a former big game biologist, I think the article is poorly written.  History has taught us that when predator populations in the west were nearly exterminated, mainly by government poisoning campaigns, game populations exploded - even though the range was grazed far more heavily than it is today.


Essentially, livestock removed so much of the low annual vegetation that it mimicked the habitat effect of decades of drought.  I would bet dollars to donuts, those fawns were fairly small, and died in droves during tough winters - but otherwise survived, and mule deer were far more productive - not in terms of birth rates, but survival. 

The reason being, except for severe winters, in the northern half of the western US, nearly every fawn that dies, succumbs to predation.  Predation rates skyrocket when hiding cover is poor and fawns grow slowly due to limited forage - but that is only the case if there are predators.  In a predator-free landscape, survival is going to be high (except winterkills).  That was essentially the case from the early 1900s, to the mid 1970s (Nixon's Executive Order banned the use of 1080 to poison predators in 1972, effects of the ban were seen by the late 70s.  Reagan reversed Nixon's ban in 1982, but EPA continues to impose a ban.)

Since 21st Century America is not going to allow the re-extermination of predator populations with poison (hell, we'd be lucky to get back body-gripping traps!), managing game populations in the presence of predators - especially robust predator populations like we've got - habitat quality becomes crucial for perpetuation of game populations - young need security to hide from predators, and high quantities of high quality forage to get as big as possible as fast as possible, both to minimize the period when they are extremely vulnerable, and also to have enough energy during mild to average winters to deal with the added energetic burden of being hunted.

Even when the herd size is being maintained, there is a much smaller surplus that can be taken by hunters because so many of the animals excess to recruitment needs feed predators rather than being shot by hunters. 

As for density-dependence, that really only is a factor when predator populations are an insignificant cause of deer mortality - and then, in that case, densities must rise to extremely high levels before the deer damage their habitat to the point of die-off.  This is also much more likely to occur in southwestern, rather than northwestern US with mule deer, as there is so much less annual forage production under normal conditions - read up on the Kaibab Plateau mule deer for the textbook example.  Even then, it is not until adult does are STARVING to death that density dependence kicks in.

Even without predators, we hit social carrying capacity here in Washington long before the habitat becomes limiting - severe winter the sole exception.  What is social carrying capacity?  That is when people are complaining about too many deer vehicle collisions, ag growers are complaining about crop damage, the people who just built a house on the winter range lose $10,000 worth of arbor vitae and roses, timber companies are complaining about damage to seedlings, etc. - we crank out the doe opportunities long before the population is limited by habitat - severe winter the sole exception.

Thanks DOUBLELUNG

couple points

I don't think this article was meant to be an all encompassing article on predator/prey relationships, but rather just a couple of observances that didn't mesh with the current main stream thinking.  A couple important ones most of us already knew.

overgrazing isn't such a problem anymore except perhaps small pockets where landowners do it to their own property and on public lands where wolves herd the animals to certain areas, usually their offload point, leaving the larger portion of the graze lease relatively untouched.   


I totally agree on habitat limitations, we've a long ways to go to reach carrying capacity for summer time use.  I'm a fan of artificial winter habitat as the carrying capacity in the winter months sets the limits.  If we bolster winter habitat with feeding stations the spring green up will take care of the rest of the 9 months.


I'd also like to add that we as a state are no where near desired take levels by hunters.  We're seeing single digit success ratios some as low as 1% with most of the NE hovering between 2-5%., if that were up near 20-25% then I'd be a little more tolerant of unmanaged predators.

[Maverick]

I'm not wanting wolves to reach 15bp. I huts want to start hunting them now before it's anymore too late.  It'd be nice to have hound hunting for cougars again in this state. And double lung you're correct on your post. But with just hunting (no poisoning or shooting from choppers or anything like that) extincting any predators is pretty well impossible.

[sakoshooter]

I started a post on this when I first received the email. No mention at all about wolves being suspected. Funny huh?

[Special T]

The devil in the details is that we likely ARE at 15 BP but they just arent documented. Documentation should be our push, but its hard to get excited to "help" when we are being slow played by the powers that be.