Preditors and Predation

July 24, 2009 by  
Filed under Articles

Predators and Predation

by: Todd A. Black

Photo Credits: Vincent Martinez

You don’t have to talk to very many landowners or even sportsmen and mention the word predator to get them excited.  “There’s way too many predators out there”, “predators are the problem”, and “what are we going to do about all the predators out there”are statements I hear all too often.  Are they justified?  Are they true statements or are they just pointing a figure at one thing that we can do something about and see the results?542725806_fmd08_9969-ws

Its basic ecology,a predator that kills its prey impacts that animal directly andto some extent may impact the population of a given area. The big question is how muchand what is that impact? If an individual animal’s death has noeffect on the population such that it is replaced by another and numbers stay the same or increase, its death is termed ‘compensatory mortality’on the other hand its death has an impact on the population such that the overall population continues to decrease, its death is termed‘ additive mortality’.  There havebeen volumes of research published on predators and prey and as with most research the data shows mixed results in some cases predator populations are too high and impact their prey, other studies show no evidence of predation being a limiting factor on a population and some are just ‘inconclusive’ in the findings.  Because there is rarely a clear definitive answer, one of two opinions/sidesusually surfaces. Those who oppose the underlying reasoning attack the researchand conversely, those who support its conclusions beat the drum even louder. Simply stated, if the research shows coyotes impact mule deer, people who like coyotes have problems with the results, but to the landowners and sportsmen who have claimed that coyotes are killing the deer, the research shows exactly what they have been saying all along.

My Perceptions on Predators

In my lengthening career with I think I have come almost full circle, especiallywhen it comes topredation on mule deer. Back when I was a teenager and knew it all, I subscribed to the rural red neck philosophy that “the only good predator isa dead one”. I spent hours hunting predators, especially coyotes. I did this simply because I thought it would create more ‘muleys’. When I started my career at college, I found out I really didn’t know it alland started to learn about predators and prey. I was taughtthatpredators don’t always impact our game populations, because they only take the sick and weak, predators can’t and won’t eat themselves out of house and home, there are cyclic relationships between predator and prey.  As I learned more about predation and actually digested the research/data I started making observations and applying those observations with what I was learning.

So what have I learned, first as I pointed out research isn’t always convincing and conclusive, research isn’t done long enough, it doesn’t always ask the right questions, and doesn’t always use the best methods.  From what I have observed, read, and studied, I now believe what we are seeing more of here in the west, especially with our deer herds, is that predators can and arehaving a negative impacton localized populationsin many areas. As I think about this, I think I have twopretty good theories to support myideas, so, I will tell you why I am going down the predators are impacting our deer herd road. First, there has been big changes in how we implement our predator management strategies, and secondhas to do with elk and the predator pit hypothesis.

Predator Management; Now and Then

How we view and ultimately manage predators has changed significantly over the past 40 years. There isn’t enough room in this issue to paint the picture of how Wildlife Services (USDA Dept of Agg. APHIS) poisoned, killed, gunned, trapped, and addressed predators in the 50’s through the early part of the 1980’s.  Long and short of it, we don’t even come close to taking the number of predators now that we did then.  To think that this intensive predation management didn’t greatly improve or increase our deer herds is comical.  In fact there is evidence that shows we likely had deer populations well over carrying capacity such that they were impacting their own. habitat.  We likely had artificially high populations of deer herds in many areas but that is when mule deer were king and everyone hunted and the days that many of us remember and wish we had again.542758998_fmd_7128-c2_wsl

While predation management practices still continue, fewer people pursue, trap, and hunt predators. Wildlife Services arekilling fewer predatorsbecause of environmental restrictions (but mainly because we have fewer sheep ranchers) and a predatorbountiesonly happen in selected counties in one state that I knowof. In contrast, less than twenty years ago many states allowed unlimited harvest of bears and lions, most had some sort of bounty system for coyotes and foxes. Twenty years ago, it was a rarity for me to see a bear let alone a lion, now it seems a rarity if I don’t see severalbears and at least onelion on my various outings each year. Today, bears and lions are intensely managed in most western states today. Most states now manage bear and lions are managed as a big game species, have quotas or limited opportunity units where the sex, age, and area of harvest are closely monitoredas to not allow too many animals to be harvested. To a certain extent even the way we as sportsmen select the large mature males in our harvestare allowing them to increase. Every biologist knows you control population numbers through the harvest of females, not the males. But, by continually selecting against the big mature tomsand boars, which everyone wants to throw on their wall, are we are allowing their population to increase by taking awaytheir own population regulators. Certainly, one could make a valid argument that our predator management philosophies and practices havehad a direct impact on our deer populations over time while allowing the predators to increase.

Elk, Elk, and more Elk555437098_em_2733_pfws-1pm-1

If you read my last article you will know I talked about elk.  I really didn’t talk about elk in the sense of them being a secondary prey source for our larger predators but let’s discuss it now.

So elk are everywhereand their populations are escalating.  What does this mean for the predator? Simple answer really, there are more groceries on the table. Normally there is an intricate balance between predator and prey(one predator and one prey). However, when there is a secondary prey source to choose from at the store, it is unlikely a predator will starve to death even if itsprimary prey decreases. I think this is what we are seeing with our deer and elk herds. Deer numbers are down and are fewer and farther between but elkare plentiful. This shift makes it possible for predator numbers to remain stable or even increase when deer numbers continue to decline.

This alteration in the predator prey relations is called the ‘predator pit hypotheses’. It states, when a primary prey (in this case mule deer) are reduced in numbers by a natural or even unnatural event (over harvest, winter kill, drought, loss of habitat, etc.), a predator species can increase or remain stable and continue to suppress their primary prey if they have a secondary prey (in this case elk) which they can switch to. How can we have increasing populations of coyotes, lions, bears, and elk and expect our deer to remain stable? The system is out of balance and it doesn’t favor mule deer. Predator management is an important aspect of mule deer management and steps need to be taken to keep predation in line with current deer populations.

What can be done?

For the past several years, one of my favorite researchers to read when it comes to predators is Guy Connolly of the USDA Wildlife Services in Colorado.  Guy pretty much shoots straight when he says, “ predator control is justified when it will produce substantial increases of game at a reasonable cost, when the extra game production is worth more than the monetary and non-monetary cost of producing it and when the increased game production will be used”.  What leave us hanging and are difficult questions to answer is.  What is justified?  What is substantial, and what is worth it?  I don’t think any of us would argue that we could use more mule deer but is it worth the cost is our habitat in condition to support more game, if we are using public tax dollars to address predators is it justifiable to the non-hunting public?

Predation management isa complex issue and we have to be realistic about how we implement predation management programs. With all the animal rights groups and the public opinion out there we just can’t declare an all out war on predators like we once did. We can’t just go out and eliminate all of the elk either. So what can be done? What can we do to help? I think we need to work hard and close with our state and federal land management agencies to support and encourage some sort of predation management particularly in those areas that are below objectives in fawn do doe rations and in those areas that are highly fragmented.  We need to work to identify funding mechanisms that will help to defray the cost and we need to develop sound monitoring techniques to determine if our efforts had any positive results.  The key as was pointed out is economics, social aspects, and monitoring. The stresses and issues that mule deer face and will have to overcome into the next generation are almost saddening.  Our management actions now will almost assuredly solidify their fate into the next 10-20 years.  While predation management isn’t the only issue and obstacle that mule deer face, it’s certainly one that every state and private management plan should have as part of their tool box.

Is habitat management the answer for predators555437132_em_2746_pfws-1pm

A parting thought about habitat and predators.  As we look across the landscape, I think it is easy to identify certain changes in habitat.  A large portion of it has changed to houses while other has burned up and been converted to seas of cheat grass.  Other changes have occurred so slowly that we may not really see the changes or understand what impacts these changes may have on game populations.  Truthfully, if we had ‘good’ habitat, management predators would likely be less of an issue.

To manage predators we need to manage our habitat.  Habitat is the primary factor we need to concentrate on in maintaining ‘good’ sustainable populations of mule deer.  Believe me, spending money on habitat improvement projects is far better spent than on a quick fix of killing predators.

It all starts with the bucks?

May 27, 2009 by  
Filed under Articles

FAWNS-BUCKS-DOES, WHERE DOES IT ALL START?

By Todd A. Black

I’ve really had to bite my tongue these past few weeks with all the internet chatter about Utah’s mule deer management plan. It just seems so much of it has all been about more and better ways with more opportunity to harvest mule deer. That is a hunting plan not mule deer management. I really believe strongly if we don’t put management 1st we won’t be hunting at all 20 years down the road.542779156_mmd06_9911ws

Photo by Vincent Martinez Photography

A few years ago, Terry Messmer (my boss) wrote an article titled ‘It all starts with fawns’. In this article he discussed the importance of fawn production and survival being the key to success for your deer herds. In the last two paragraphs he discussed the importance of buck age structure within a given population and the role they play in the fitness of a population. He stated, “reduced numbers of mature breeding males in breeding populations could further disrupt mule deer reproduction if immature bucks are unable to breed (or might not know how to court and breed) available females”. Having a good number of mature bucks in the population is a very important part of mule deer biology. So my question is, does it really start with the fawns, or does it start with the mature bucks? I guess this is kind of like asking which came first the chicken or the egg. No doubt the health and fitness of the does is equally important as well. If does are not ‘fit’, they likely won’t even be breed. Terry goes on to say that the timing and strategies of our harvest and the increased recreational access during the fall and winter months could possibly be disrupting the biological mechanisms regulating mule deer reproduction. These factors may inadvertently be contributing to reported declines in deer abundance.

How about we discuss the importance of age structure amongst the population of bucks and the role the older bucks play in mule deer population. Then we’ll briefly discuss how you and I fit into the mule deer management equation.

Does it all starts with the bucks?

Have you ever wondered what goes on in bachelor groups of bucks during the long summer months? While I do spend a fair amount of time watching them, I would love nothing more than to spend an entire summer or four day in day out watching one group of bucks interact, establish a dominance hierarchy among themselves, and learn new and undocumented behaviors; what a great summer job. A close friend and partner theorizes that during this time the younger bucks are learning form the older bucks how to be bucks. This might sound kind of silly but there is likely some truth to this theory. Much like the males in the human population there is a great deal of learning and maturing gleaned from the younger bucks observing older males. They learn what to eat, where to water, where to hide, how to act, how to treat the ladies and generally just how to be a buck. Without a doubt, these type of learned behaviors are crucial and key to the survival of the species. So just what is a mature buck? How do we know they are there?

Some biologist may classify and tell you a mature buck is a 2 year old buck. This is mainly because this buck is sexually mature. All this really means is that its testicles have dropped and it can produce viable sperm. However, a buck really doesn’t become ‘mature’ until he’s somewhere around 5 years old. Not only are many physical characteristics of the buck fully developed but the buck has had time to grow and mature and knows how to be a buck. The question now is, are we losing some of these important learned behaviors because we don’t have the mature bucks we once had?

So what does all this mean?542756376_mmd07_1d0619-ws

The natural history of cervids dictates that the females will select and breed with the dominant mature male. Generally, this is determined by body and or antler size. This selection takes place during what we call ‘the rut’. The rut of mule deer, in most western states peaks around the third/forth week in November. Mating with a mature buck should ensure a strong/’fit’ offspring and builds a healthy population. At least that’s the theory. Unfortunately with the declines of deer in the west, there aren’t too many places where you find ‘mature’ bucks doing the bulk of the breeding. Habitat fragmentation, highways and roads and urban sprawl have isolated and fragmented traditional winter ranges and breeding grounds. With these groups of does scattered hinder and yawn, it’s next to impossible for one or two mature bucks to breed 30 does let alone 100 or more. What is more typical in many of our herds is the two and three year old deer or even yearlings are doing the majority of the breeding. Are they capable of doing so? They are. The genes are still there, it can’t be bad for the population, right? Well, it might be and here’s why.

Could it all start with the Does?

A doe likely won’t breed with a scrawny pencil neck buck during her first estrus cycle. However, if she is still ‘fit’ she will come into estrus again 3-4 weeks later. Now, she may just decide that pencil neck is better than nothing if Goliath is still absent. This really isn’t helping our deer herds.542782859_mmd06_9646ws

The gestation period of a doe is 200 days give or take a week or so. Given that, lets do some math I know it hurts but it’s simple. Lets say doe ‘A’ is bred on November 18th, given a 200 day gestation, the fawn should hit the ground right around the 30th of May. Doe ‘B’ is bred on December 23rd (her second cycle) given the same gestation period, the fawn hits the ground on Independence day. Does anyone see what is happening here? Fawns born in May/June are likely to weigh more, be more ‘fit’, and better to withstand predation and make it through a bad winter than those born in July/August. These fawns go into the winter being less ‘fit’, weighing less, making them more susceptible to disease, predation, and extremes in weather. Which can lead to higher fawn mortality, less recruitment into the population and lower doe to fawn ratios? Ask yourself when the last time you saw a fawn with its spots still in late August/September. This really shouldn’t be happening if all the does were bred in late November early December, but I see it with more and more frequency.

Could we a part of the problem, does it start with us?

This is a tough question. It’s a biological, social, and economic issue. What are we to do? For starters, we just can’t continue to manage for quantity during these times of famine. Maximum sustained yield goes out the door with extremes in weather. One solution might be to manage for quality rather than quantity; another might be to simply reduce the number of tags sold and reduce harvest. Obviously this presents a few problems. Who is going to be the first to give up their tag for a year or three? I know in Utah it would be cut throat to give up a tag. Ask your state agencies how much money they can live without.

In summary, I don’t think we can continue to allow our immature bucks to do most of the breeding. We need those mature males in the population. We need ‘fit’ healthy fawns to make it through the dry summers and the cold wet winters. We can’t be harvesting 70-80% of our yearling bucks during these harsh times and expect things to recover over night or from year to year. We must manage for an even age distribution of bucks in the population through restrictions and reductions. It’s important for us to realize this. We as hunters just can’t continue to kill anything that has antlers and expect our mule deer population to increase. I’m not saying we all need to be trophy hunters either. But just maybe we don’t have to kill a deer every year to be a real hunter.