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#53971 - 08/30/01 02:55 PM Statistics
Dan K Offline
Seasoned Member

Registered: 05/10/01
Posts: 149
Loc: SW Oregon
I saw a post about a road killed Mt. Lion in Iowa and it brought to mind a question regarding statistics.

Is there a way to determine population of a species using road kill numbers? I'm sure one kill is too small a sample to reach a reliable figure, but it seems like if one is hit on the road, there must be "X" more of them still running around the countryside. Just what that "X" number might be is the question.

Here's another example. Wolverines are supposedly extinct in Oregon. However, several years ago, a wolverine was hit by a car on I-84 in the Columbia Gorge. Since this is a species that typically stays as far away from roads as possible, it seems pretty unlikely that the one that was hit was the only one that existed in Oregon.

Any thoughts on this?

-dan

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#53972 - 08/30/01 06:33 PM Re: Statistics
Anonymous
Unregistered


I pay a lot of attention to RKs. It's hard to draw any conclusions from a single wolverine. They say one mouse, or one cockroach, you figure there are a hundred more.

But, with coyotes, it can be seasonal. Like the signs that warn that deer are crossing the road for the next five miles. Well, sure, they migrate downhill for the winter. But, where are they right now? With coyotes, it's a pretty sure bet that the dead ones you see on the Interstate got hit at night. Guess that would apply to at least 75% of them. But, the places they hunt at night might be several miles from where you would have the best luck hunting during the daytime.

I consistantly see dead coyotes in certain places. Between LA and Las Vegas, if I see them, (and that isn't assured), but generally they are on either side of Halloran Grade. Same thing driving to Phoenix. I see more coyotes along Centennial Wash, and if I had the urge to try a stand along that stretch, that's where I would spend some time....

There is a particular place that I used to always see crossers in the daytime, way down south. It never was my destination, but after seeing such numbers; one day, I had some time to spare. What a fortunate thing. I found a road that was almost invisible that ran along a fenceline, and a hidden water tank less than a half mile in. I'm not exagerating; this road never fails, and every time I use it, there aren't any tire tracks. However, come to think of it, I've never noticed a RK anywhere close?

But, alive or dead, might pay to check it out. Might be a hundred more, just over that hill!

Good hunting. LB

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#53973 - 08/31/01 09:00 AM Re: Statistics
Curt Barrett Offline
PM senior

Registered: 04/21/01
Posts: 5144
Loc: Pacific Northwest
I know in WA they keep track of those numbers and use them to help determine deer pops. Have to agree with Leonards obsevations relating to other species.

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#53974 - 08/31/01 10:36 AM Re: Statistics
Critr Gitr Offline
Retired staff

Registered: 04/21/01
Posts: 2456
Loc: Oak Ridge, TN
Here is another factor to consider. I have started seeing a notable number of road kills in areas where I haven't noticed any for months.

Young, dumb coyotes, who haven't learned to avoid cars???

------------------
Critr


www.SaguaroSafaris.com

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#53975 - 09/02/01 02:27 PM Re: Statistics
steve allen Offline
Predator Master

Registered: 01/05/02
Posts: 88
Loc: Bismarck,ND
Dan K.--Yes indeed, one can often determine changes in mammal populations by an index using animal observations; road kills or live animals. One needs to weight the data by miles driven and sizes of survey areas (we used counties) to get a true look at the data. We need to do this, because the more miles driven and the larger the survey area; the more animals (alive or dead) one will find. Without this weighting procedure one biases his data with these variables, thus preventing an accurate look at the impact of population changes.

We utilized live animal sightings in North Dakota gathered by rural mail carriers for almost all the fur species as an index to population changes, annually. For red fox and coyotes we had other data utilizing actual population counts to compare to the roadside surveys to determine accuracy. We found that the roadside data very accurately determined population changes for red fox, and moderately accurately for coyotes. We did not have actual population size data available for the other species, but the assumption is that the roadside data would very likely be representative of changes in population to some degree. Because of often small numbers of animals seen/1000 or so miles driven, one needs really large sample sizes to determine population changes.

As Leonard very correctly points out one can still use this technique in a modified form to determine localized areas with high animal densities for hunting or trapping. If you travel around a lot in your work or know others that do (e.g. UPS drivers, delivery people, truckers, etc.), one can record where and when and what is seen and potentially find an absolute "gold mine" of a hunting or trapping area. Keep in mind that because of territorial behavior of coyotes and red fox (and virtually all other canid species), they spread themselves out over large pieces of real estate quite uniformly (e.g. 10,000 sq. miles or so at least) almost regardless of land use, topography, cover type or anything else. Thus, the data you accumulate may just be the tip of the iceberg of an unknown coyote paradise and may be virtually untapped re: hunting or trapping especially in more remote areas.

Now there is an interesting concept to think about, huh. Like Leonard again correctly points out, somebody has to find these hotspots; why shouldn't it be you?

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#53976 - 09/02/01 04:20 PM Re: Statistics
Dan K Offline
Seasoned Member

Registered: 05/10/01
Posts: 149
Loc: SW Oregon
Thanks for all the replies. Good info here.

Steve - a further question for you. If the coyotes spread themselves out uniformly regardless of habitat, land use, etc., then wouldn't this seem to preclude the existence of any hotspots? Unless you're talking about a particularly large family group occupying a standard range, or a place that hasn't been impacted by hunting or trapping. But the latter is kind of a negative definition of a hot spot.

Now as Leonard has pointed out, he's found at least one spot that does seem to always produce coyotes. Has he just found the nexus of several home ranges, or a travel funnel, or something else? What could be the explanation for this particular place being so productive in comparison to the others?

What I'm wondering is - Do you think there are the same number of coyotes in this area, but for some reason they utilize this particular spot more than others?

Sorry to keep bugging you on this, but I guess one question begets another.

-dan

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#53977 - 09/02/01 06:51 PM Re: Statistics
steve allen Offline
Predator Master

Registered: 01/05/02
Posts: 88
Loc: Bismarck,ND
Dan K.--Not to worry; you're not bugging me in the least. I really like good discussion, and your questions are excellent!

What I was getting at is that if you find an area with lots of coyote/red fox/whatever observation (alive or dead), it may be a very good indicator of an area with significantly higher overall population densities. Data we gathered in North Dakota indicates the size of such an area could easily be 5,000-10,000 sq. miles especially in remote country. One would then need to do some serious exploring to see what he had really found. Tracks are a good indicator, if the soil is such that tracks are retained for a length of time.

Now, within these broad areas there could easily be areas with even higher localized densities. This could easily occur during the fall/winter, because of dispersal behavior. Many pups and some older animals will disperse cross-country during this time; almost no resident adults disperse. Many trappers have had a certain trap set that produced animals day after day/year after year at virtually the same spot. What happens is that what looks good to 1 coyote/fox etc. often looks good to others; especially dispersing animals moving across country. Thus, the faster one can get to these localized "hotspots" and pull out the animals (hopefully with no mistakes, missed shots, etc), the quicker new animals will move into to fill the void you created during the fall-winter period. If everything worked exactly right, one could easily go to the same location every few days, and have an excellent chance of being successful.

Hopefully, I answered your questions. If not, or if you have more, be sure to post back again. We will keep talking for as long as it takes to get everything answered for you.

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#53978 - 09/02/01 07:32 PM Re: Statistics
Dan K Offline
Seasoned Member

Registered: 05/10/01
Posts: 149
Loc: SW Oregon
Thanks Steve! That cleared it up for me.

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#53979 - 09/16/01 03:20 PM Re: Statistics
Steve Craig Offline
Seasoned Member

Registered: 09/09/01
Posts: 220
Loc: Cottonwood,AZ USA
Hi Dan K,
How are you and your dad doing? I haven't been on here for awhile and saw your post, and was wondering how you are doing with that new caller you got. A mutual friend said you were cleaning up on the coyotes! Any luck with the lions yet?
Steve

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#53980 - 09/16/01 07:40 PM Re: Statistics
Dan K Offline
Seasoned Member

Registered: 05/10/01
Posts: 149
Loc: SW Oregon
Hey Steve.

I'm doing fine. My dad is too. I took the caller out the first day I got it. The third stand I made, I had 5 coyotes circling all around me and howling like crazy. Because of the property boundary, I couldn't set up in the best spot though, and I didn't get any shots through the brush.

I'll be going after lions during deer season. I haven't made any serious stands for them yet, but I'm seeing lots of sign all over. There sure are a whole lot of 'em in this area.

It's good to hear from you. I hope everything's going well with you and your family.

-dan

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