Post by: bearpaw on January 20, 2015, 10:02:12 AM
Deer, Predators, and Drought
New research holds surprises
By Rory K. Aikens
Reprinted from Arizona Wildlife News
July-August 2004
Quote
An ongoing research project on the 3-Bar Wildlife Area near Roosevelt Lake is helping biologists to better understand-and to an extent redefine--the predatorprey relationship.
The study's findings so far indicate that predators may have a more significant impact on deer populations than biologists previously thought. The prevailing biological belief is that habitat conditions are the primary controlling factor for deer populations, not predation. The long-term deer study at the 3-Bar is punching holes in parts of biological theory, and others.
Jim deVos, research chief for the Arizona Game and Fish Department, says the findings have many biologists scratching their heads. Despite a prolonged drought, biologists are seeing deer densities within the predator-proof enclosures rivaling those in places like the pri'me whitetail country of the southeastern Unitcd States. Yet deer densities outside the 3-Bar enclosure have experienced significant declines during that same period.
Quote
3-Bar is a unique outdoor lab
The 602-acre Walnut Canyon Enclosure in the 3-Bar Wildlife Area is located in the Tonto National Forest. The Walnut Canyon Enclosure is a fenced area of almost one square mile that provides a unique outdoor wildlife laboratory for biologists.
This predator-proof enclosure has been used for more than 30 years to study mule deer declines and for other research as well. Two mule deer declines have been documented in the western United States since the 1960's. The exact reasons for declines are varied and often difficult to pinpoint.
"The original 3-Bar mule deer study in the late 1970's found that fawn survival was 30 percent greater inside the enclosure than outside during a six-year wet period. The current 3-Bar study shows that despite one of the worst droughts in the past 700 to 1,000 years, fawn survival has remained high in this predatorproof enclosure", says deVos.
Outside the enclosure during the drought, fawn survival rates and mule deer populations have plunged to the lowest numbers in the past half-century.
During 2002, which was the driest year in Arizona's recorded history, the fawnto-doe ratios within the enclosure were 100 fawns per 100 does. Outside the enclosure in Game Management Unit 22 the ratio was 18 fawns per 100 does. "The only significant difference between the two areas is the absence of predators in the 3-Bar enclosure," Ballard says.
Quote
3-Bar study challenges theories
The 3-Bar deer study findings challenge many accepted biological theories.
For instance, de Vos says, biologists have long believed that deer are "density" dependent, which means that once deer density ratios get high, deer experience a reduction in fecundity--the physical ability to reproduce. "That's not happening on the 3-bar. That tells us that density dependency may not be a valid theory or hat the threshold for it is much higher than anyone thought."
Another generally accepted biological theory is that habitat conditions, not predation, control deer numbers. "That theory may be true when weather and habitat conditions are good, such as our study during the 1970's in the 3-Bar. However, we have had a decade-long drought in 2002--the driest year in recorded history--yet deer numbers, densities, and reproduction have remained as high as during the wet years," de Vos says. "The absence of predation is the only variable that has changed."
read more: http://www.gardnerfiles.com/3-g%20Arizona%203-Bar%20Study.pdf (http://www.gardnerfiles.com/3-g%20Arizona%203-Bar%20Study.pdf)
Post by: jasnt on January 20, 2015, 10:07:34 AM
Post by: huntnphool on January 20, 2015, 10:15:32 AM
The title should actually read Deer, Predators, Politicians and Drought
Post by: bearpaw on January 20, 2015, 10:23:10 AM
http://www.gf.state.az.us/w_c/research_fire_predation_mule.shtml (http://www.gf.state.az.us/w_c/research_fire_predation_mule.shtml)
The effect of fire, predation and vegetation quality on mule deer habitat use and fawn survival
Mule Deer BuckBackground:
Western states biologists have documented 2 declines in mule deer numbers since the 1960s. The reasons for decline are varied and often difficult to pinpoint. Because mule deer are so important to sportsman and the general public, the Arizona Game and Fish Department began to research desert mule deer decline by constructing the Walnut Canyon Enclosure at the Three Bar Wildlife Area in 1970. This predator proof enclosure allowed us to closely examine the effects of predation on fawn survival. In the initial study, we determined that fawn survival was approximately 30% greater in the absence of predators. In 1988 the gates to the enclosure were opened to allow animals to move in and out of the area until 1997. In early May 1996, the Lone Fire burned approximately half of the enclosure, so we once again used the enclosure and examined mule deer habitat use in predator-free, burned and unburned environments. In 2000, we introduced coyotes for 6 months to see if their presence changed deer habitat use. Even during our current drought, the predator free deer population continued to increase, prompting us to continue investigating the effects of different mule deer densities, vegetation quantity and quality, predation, drought, and deer nutritional condition in and outside of the enclosure have on mule deer fawn survival.
Location:
The 602-acre Walnut Canyon Enclosure (slightly smaller than a square mile) on the Three Bar Wildlife Area in the Tonto National Forest south of Roosevelt Lake in central Arizona.
Approach:
Mule deer releaseVegetation data are collected each spring, summer, autumn, and winter, and deer density counts are taken each fall in a deer drive. We measure vegetation inside and outside the enclosure to look for differences among seasons and years at different deer densities (high inside, low outside). The deer drive is conducted using 60-100 employees and volunteers who form a line across the entire enclosure and walk from one end to the other. Each animal that passes through the line along the way is counted once, providing accurate information on the number deer and peccaries in the enclosure each year. Two graduate students from the University of Arizona completed the fire ecology portion of the study in December 2002, and 2 new graduate students (ASU East and Texas Tech Universities) will continue to work with research branch biologists over the next three years to look at habitat quality and deer nutritional condition.
Benefits:
The use of a large enclosure is similar to having an outdoor laboratory, and allows to control the predator component of population regulation. The original study that found fawn survival was greater inside the enclosure was during a six year wet period. However, since we closed the gates in 1997, Gila County, as well as much of the rest of the state, is in the worst drought that has occurred in the last 700 to 1,000 years. We did not expect the mule deer fawns within the enclosure to survive at as high of rates as they did in the wet period, but they have. Leaving us with the question, are predators more important than habitat in controlling deer numbers? That is why we have switched our emphasis to the habitat quality and deer nutritional condition. Certainly, there must be an interaction between habitat quality, deer nutritional condition, predation and fawn survival. Hopefully our large outdoor laboratory will help illuminate what conditions desert mule deer fawns need for optimal survival.
This project was conducted under the direction of
Stan Cunningham, Arizona Game and Fish Department, 5000 W. Carefree Highway Phoenix, AZ 85086-5000 .
Post by: KFhunter on January 20, 2015, 10:25:23 AM
Post by: bearpaw on January 20, 2015, 10:40:30 AM
http://www.aphis.usda.gov/wildlife_damage/nepa/EA%20Predator%20Damage%20Assessment%20Pub%20Land%20AZ.pdf (http://www.aphis.usda.gov/wildlife_damage/nepa/EA%20Predator%20Damage%20Assessment%20Pub%20Land%20AZ.pdf)
Post by: Maverick on January 20, 2015, 11:18:00 AM
Post by: huntnphool on January 20, 2015, 11:40:01 AM
Release the hounds! Call in some coyotes, issue some wolf tags and I'll bet washingtons mule deer population will do better!
How does increasing the wolf population translate to rebounded mule deer herds? :bash:
Post by: elkaholic123 on January 20, 2015, 12:02:03 PM
I don't see where he said increase the wolf pop? I think he wants to eliminate some :dunno:Release the hounds! Call in some coyotes, issue some wolf tags and I'll bet washingtons mule deer population will do better!
How does increasing the wolf population translate to rebounded mule deer herds? :bash:
Post by: huntnphool on January 20, 2015, 12:13:03 PM
I don't see where he said increase the wolf pop? I think he wants to eliminate some :dunno:Release the hounds! Call in some coyotes, issue some wolf tags and I'll bet washingtons mule deer population will do better!
How does increasing the wolf population translate to rebounded mule deer herds? :bash:
Pay attention Jerry, to hunt wolves in this state we need to reach the 15 BP target, to reach the 15 BP target, the wolf numbers will need to increase. ;)
Hunters should be hoping that we never reach the 15 BP target, we have too many wolves in this state already!
Post by: elkaholic123 on January 20, 2015, 12:18:00 PM
Post by: huntnphool on January 20, 2015, 12:22:41 PM
They are not referring to wolf hunting seasons here, they are referring to big game seasons!
So go ahead and keep pushing for us to reach the 15 BP target, but don't bitch and complain when you reap what has been sown!
Post by: huntnphool on January 20, 2015, 12:24:05 PM
Yes I know Rob but I think Maverick just wants to eliminate them NOW :chuckle:
Mav understands that wolf tags can not be issued until they are delisted. ;)
Post by: KFhunter on January 20, 2015, 04:05:07 PM
I will also remind those of you that did not attend the meetings, 99% of you, and those of you that have not read the wolf plan, likely 99% of you. It's clearly written in the plan that should the ungulate numbers drop to a point that is not sustaining the wolf population, "hunting seasons may necessarily need to be adjusted".
They are not referring to wolf hunting seasons here, they are referring to big game seasons!
So go ahead and keep pushing for us to reach the 15 BP target, but don't bitch and complain when you reap what has been sown!
They can't even get to that part until the know what the ungulate numbers are, and according to the plan if they see ungulate numbers severely affected they'll initiate a 3 year ungulate study. WDFW has no clue to ungulate numbers on the east side.
We've got a looooong ways to go in this wolf war of Washington state.
Post by: JimmyHoffa on January 20, 2015, 04:17:07 PM
But isn't there all kinds of disconnect about the ungulate populations anyways. I remember threads about the fire from last summer and lots of doe tags, the hunters feel the area herd is already having a tough time but the local biologist says deer are doing outstanding and gives glowing preseason reports. Even when the deer do take a major hit, won't WDFW probably be telling everyone the herd is robust?I will also remind those of you that did not attend the meetings, 99% of you, and those of you that have not read the wolf plan, likely 99% of you. It's clearly written in the plan that should the ungulate numbers drop to a point that is not sustaining the wolf population, "hunting seasons may necessarily need to be adjusted".
They are not referring to wolf hunting seasons here, they are referring to big game seasons!
So go ahead and keep pushing for us to reach the 15 BP target, but don't bitch and complain when you reap what has been sown!
They can't even get to that part until the know what the ungulate numbers are, and according to the plan if they see ungulate numbers severely affected they'll initiate a 3 year ungulate study. WDFW has no clue to ungulate numbers on the east side.
We've got a looooong ways to go in this wolf war of Washington state.
Post by: KFhunter on January 20, 2015, 04:28:55 PM
Post by: DOUBLELUNG on January 20, 2015, 04:55:36 PM
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.
Post by: KFhunter on January 20, 2015, 06:04:26 PM
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.
Post by: Maverick on January 20, 2015, 08:05:45 PM
Post by: sakoshooter on January 22, 2015, 10:11:07 PM
Post by: Special T on January 22, 2015, 10:47:04 PM