Hunting the Oldest of a Species

[YukonSean]

Good day everyone,

I have been getting into big game hunting the past 3-4 years, mainly sheep, moose, caribou and bison.
My question has to do with goal of harvesting the oldest member of a species. I have heard from hunters that targeting the
oldest animals in a population is preferable/beneficial for conservation of the species.

I have scouted around the internet but cannot seem to find any information either in support or opposition to this.
Could someone shed light on the legitimacy of this if there is any?

Thanks,

Sean

 

[Nickofthewoods]

Take Mule Deer for example. On one hand, if you knew that a certain buck was very old and his teeth were worn down to the point that he may not make it through another winter, then yeah, shooting that buck would probably not negatively affect the herd. That would be nearly impossible to tell unless you watched that deer year after year and knew how old it was. On the other hand, if you shoot a big healthy buck in his prime then maybe that could negatively affect the herd by taking out the strongest animal with the best genetics to pass along. I'm not a biologist, those are just my personal musings as I have often wondered the same thing.

 

[DoubleBroomedMountainRifles]

For Thin Horn sheep it is a 100 percent fact! Harvesting older rams is a positive for future conservation numbers. Our full curl, 8 year old, or broken horns requirements, in most of Alaska dall sheep hunts for legality have very little impact on the overall population of Dall's. A legal ram is considered a "surplus" for the most part.

 

[YukonSean]

For Thin Horn sheep it is a 100 percent fact! Harvesting older rams is a positive for future conservation numbers. Our full curl, 8 year old, or broken horns requirements, in most of Alaska dall sheep hunts for legality have very little impact on the overall population of Dall's. A legal ram is considered a "surplus" for the most part.

Thanks for the response,

I am curious if there is any science backing this? How does harvesting the oldest rams possible benefit future conservation numbers? I have always wondered this. Much like Nickofthewoods mentioned in his last comment, I would have thought that leaving the older more mature rams to reproduce and pass on their superior DNA, would be much more of a benefit to future generations than harvesting them.
I understand the restrictive nature of only harvesting full curl rams on a "managing the number of animals taken" basis, but if one shoots a younger ram, you don't really know if that is a ram with DNA you want to be passed on. Whereas if you take an old mature ram, you have the proof right in front of you just that the ram has made it to such a mature age, I would think this would be the ram to keep around.

 

[Nickofthewoods]

I'd be curious to see data or a study on this topic as well. The only literature I have read that touched on this subject was a book by David Peterson ("Elk Heart" I think) and he was talking about Elk and how hunters - for the sake of Herd health - shouldn't always be targeting the biggest Herd Bulls. Sorry I used Mule Deer as my example, they are what I am most familiar with. I have little experience with Sheep and the other species you mentioned above.

 

[Cheesehead]

Good question and thanks for introducing it.

I am not an expert, but I think the idea is rooted in the belief that a population’s health is in part based on its biological diversity. Imagine a small isolated cluster of 100 transplanted desert bighorns, including 3 mature males, 27 younger males, and 70 females. Let’s assume that the ‘most mature’ 3 males do 80% of breeding due to superior size and dominance.

If 3 males were harvested each year, and it was randomly distributed, the most likely scenario would be that 3 immature males would be harvested. In the second year’s breeding cycle, the same 3 mature rams would breed 80% of receptive females (ie, minimal ‘new’ genetics passed on to the population).

In another scenario, only mature males can harvested, and so our 3 mature rams go to the happy head butting place in the sky. In year 2, there would be an increased genetic diversity passing through via ewe-panky.

 

[Goatie]

It’s just smart in conservation to kill the oldest male that has a pretty good chance of dying that year. Why kill a deer that’s 3 when an old male in the wild gets to, at most 8-10. Potentially the 2 year old has more years.

 

[YukonSean]

Good question and thanks for introducing it.

I am not an expert, but I think the idea is rooted in the belief that a population’s health is in part based on its biological diversity. Imagine a small isolated cluster of 100 transplanted desert bighorns, including 3 mature males, 27 younger males, and 70 females. Let’s assume that the ‘most mature’ 3 males do 80% of breeding due to superior size and dominance.

If 3 males were harvested each year, and it was randomly distributed, the most likely scenario would be that 3 immature males would be harvested. In the second year’s breeding cycle, the same 3 mature rams would breed 80% of receptive females (ie, minimal ‘new’ genetics passed on to the population).

In another scenario, only mature males can harvested, and so our 3 mature rams go to the happy head butting place in the sky. In year 2, there would be an increased genetic diversity passing through via ewe-panky.

That makes a lot of sense. I sometimes forget how isolated these sheep populations are. Genetic diversity would most certainly be more desirable than the same genes (as favorable as they may be) pumping through the system year after year.

 

[Blockcaver]

Check out Valerius Geist’s work on thinhorns. He is a biologist and professor (maybe retired at this point) at the University of Alberta. He and his work is considered the most definitive on thinhorn sheep. He specifically studied Stone sheep in BC as I recall.

What I know is many rams don’t survive the winter folllowing their age 7 breeding season due to rutting so hard. They are in their prime for breeding that yr. Horn growth really slows after age 7 as well. So the age 8 or older part of legal rams is based on this. In an area I hunted Stone sheep a lot over 7 seasons there are very few 8 and up rams, greatly outnumbered by just 7 year old rams, not to mention the 5 and 6 yr old up and comers. Each yr I expected there would be a huge 8 yr old crop the following yr but it never materialized.

Note that full curl is another regulation to limit harvest of younger rams. However in certain areas a 6 yr old could be a full curl. Other areas old rams never achieve full curl or are broomed off.

Good luck, and don’t worry about hunting old rams. You won’t destroy the genetics. There is a school of thought that some of the old rams got old because they did not participate in the rut and never got run down. However, I know some of the old ones show signs of a lot of battles.

 

[Wapiti1]

You beat me to suggesting Valerius Geist. In addition to his sheep work, he has done a lot with caribou and was a big part of writing the North American Model of Conservation. Another good source of info is the management plan the state publishes every few years. CO CPW and MT FWP put out pretty comprhensive reports detailing the why of the plan.

Here is a good study from the Bighorn Canyon Herd with a lot of references to other work. It covers your question, but not is super detail: https://pubs.usgs.gov/of/2004/1337/report.pdf

Jeremy

 

[Coveyleader]

There is evidence showing that taking the top rams does effect the herd. I remember seeing something or actually talking to a renowned sheep biologist here in Colorado about this. Geist as well wrote about it.

I also think we as hunters love to use the “no teeth he wouldn't have made it another year” phrase as some sort of “feel good” statement with underlying meanings I.e. “I just shot a giant old animal” or “ I did him a favor and put him out of his misery, he wouldn’t have made it through the winter” to appease some unknown audience.


Fact is, humans have always loved big horns and antlers, but these days we have to soften the tone or we’re labeled “Sport/ Trophy hunters”

 

[WCS]

Recently there have been a lot studies conducted on the effects of age restricted hunter harvest for every species of ungulate in North America. Geist's work may be a bit dated since hes retired now, but his book on wild sheep is definitely a must own. Here's a link to a more recent one and there's lots of references to other good papers. https://onlinelibrary.wiley.com/doi/full/10.1111/eva.12841