significance of bull/cow ratio?

[trophyhill]

i was talking to a CDOW official on the phone yesterday regarding some public meetings coming up to decide if a few OTC units will go to draw units or not in the very near future. we talked about alot of different topics that brought this about. one thing that we talked about was the target bull/cow ratio #'s. the official i spoke to said the target was between 18-23 bulls per 100 cows in these particular units. do you all think these #'s are good? i don't and have my reasons but would like to hear what others think and why. any takers?

 

[nv-hunter]

Those #s seem a little low to me but coming from Nv maybe thats why our bull/cow #s run about 30 to 35 per 100. From a livestock back ground they should be just fine as long as 10 to 15 of these bulls are 4 to 5 years old or older. A mature bull should have no problem breeding 5 to 10 cows a season. jmho what are your thoughts?

 

[ElkNut1]

Anytime you can have areas with 25+ bulls per 100 cows you are in a very respectful hunting area! Yes, maturity of bulls is a big consideration, but there are many elk areas with 12-15 bulls per 100 cows, this makes for tougher hunting, our personal hunting areas fall into this category at best, at one time we did have the near 25 bulls per 100 cows but the wolves have put a serious damper on the population since the 1994 introduction! (grin)

ElkNut1

 

[trophyhill]

Those #s seem a little low to me but coming from Nv maybe thats why our bull/cow #s run about 30 to 35 per 100. From a livestock back ground they should be just fine as long as 10 to 15 of these bulls are 4 to 5 years old or older. A mature bull should have no problem breeding 5 to 10 cows a season. jmho what are your thoughts?

according to my limited research, the #'s in your area are where they should be. with lower bull to cow ratios there is a chance that some cows won't get bred and...if cows get bred by young immature bulls year after year it affects the gene pool and the genetics in future populations might not produce quality bulls. lets not forget that a spike can breed cows and the cows will let him if thats all thats available.

 

[arrowslinger21]

I have taken population biology courses in my biology degree requirements, and while it is better if there are higher numbers of bull for the sake of hunting, it is also better for the elk population in some respects with lower numbers. With a higher number of cows than bulls, there will be more calves born. For example if an area could only hold 125 elk, and only 25 were bulls, chances are the bulls there would still breed all the cows and you could have 100 calves born if you assumed they would have one calf each and they all survived to birth. Make the ratio 50-50 and now you only have 75 calves born instead of 100. More calves=more elk and a better chance to survive predation, especially in the areas with lots of wolves and other predators. Also it keeps the big boys with larger herds, which does a better job of passing on their good genetics for us hunters.

 

[nv-hunter]

I think as long as you have 10 mature bulls per 100 cows with in a reasonable area all cows should be covered during season. 1 to 10 is not going to effect breeding success. Geneticly speaking a rag horn bull at 2 years has the same genitics as he would at 6 years no diff geniticly. Young bulls just can't get the job done every time. Quality = age + genitics. Like the old joke says young bull and old bull on a hill looking at the cows young bull says lets run down and get one old bull says lets walk down and get them all.
As for the bull to cow ratio it is a standard figure so one can look at it no matter where they are. In the above example 75 bulls to 75 cows would be shown as 100/100 bull to cow ratio it has nothing to do with total population numbers. I guess when talking about this the follow up question to bull to cow ratios has to be " what are the number of mature bulls to 100 cows? and what precentage of mature bulls are the ones doing the breeding?" This info also has to be paired with numbers of elk per square mile to find out what the numbers truly are. my 2 cents

 

[trophyhill]

"I guess when talking about this the follow up question to bull to cow ratios has to be " what are the number of mature bulls to 100 cows? and what precentage of mature bulls are the ones doing the breeding?" This info also has to be paired with numbers of elk per square mile to find out what the numbers truly are. my 2 cents"


i think thats a very good point and valid follow up question. when talking "mature bulls", are we talking 5 years or older?

 

[nv-hunter]

I would think 4 or 5 to 8 or 9 would be the target age range.
As arrowslinger put in his post as long as the bull/cow ratios are within target range the herd should be growing 20/100 bull to cow works out to 1 in 5 not bad odds there.

 

[Guy]

I think a bull to cow ratio of 20/100 is a good target. Seems to be a good blend of both criteria, good hunting, a decent population of mature bulls, and a good clean healthy herd that will increase in number, barring any predation or wintering disasters. Most of the areas around here (WY) are bit shy of that number. Generally 7-12 bulls per 100 cows. I'm definitely not afraid to hunt in an area that has 10 bulls per 100 cows or even a little bit less.

 

[trophyhill]

I would think 4 or 5 to 8 or 9 would be the target age range.
As arrowslinger put in his post as long as the bull/cow ratios are within target range the herd should be growing 20/100 bull to cow works out to 1 in 5 not bad odds there.

if 1 in 5 are mature bulls then the #'s "could" be sufficient depending on certain variables such as space and nutrients and # of cows 2 years or older. according to what i just read, if mature bull counts are down or non existent then yearlings will perform the task but....the yearlings breed 1 month later and 1 month shorter, thus lessening copulation rates. it also effects birthing by pushing birth dates into July when the key nutrients that calves need are past their prime making for a less healthy calf come winter time and perpetuating the late birthing cycle where yearlings do most of the breeding. which in essence would produce less quality bulls even though yearlings are capable of breeding.

a study by a guy named Smith (Bruce Smith?) indicated that pregnancy rates drop from 77% to 61% where yearling bulls were the prominant breeders in Roosevelt elk and branch antlered bulls dropped from 8 to 5 per 100 cows.

a guy by the name of Hines also indicated that when the number of pre season branch antlered bulls dropped from 39 to less than 10, pregnancy rates dropped from 67% to 47%.

a guy by the name of Squibb reported that pregnance rates in a northern Utah herd were significantly higher where there were 41 bulls per 100 cows vs another northern Utah herd where there were only 15 bulls per 100 cows with few mature bulls.

something else i just read was a guy named Bubenik suggested 25 mature bulls per 100 cows are necessary.another guy named Noyes states that 18 mature bulls per 100 are necessary and Hines concludes that 3-10 mature bulls per 100 cows are needed so....it appears that even amongst "experts" there is conflicting opinions. i just wonder what or if there were significant differences in habitat in these 3 studies.

i love learning about elk.

 

[Howahunter]

You would have to know many factors to know if 18-23 was a good target. it is a respectable target for sure but what other factors are playing a significant role in the management of that elk population? Sure you could shoot for the moon but then hunting becomes restricted and elk tend to eat themselves out of home when numbers escalate just like most any wild animal. Were they talking 18-23 mature bulls per 100 cows or was it just a male:female ratio? Lots to ponder about when it come to ratios and where a state needs to manage certain populations.

 

[Firearrow]

I am no Biologist, but, I think it depends on one big factor first. Are you trying to produce a trophy unit, or a "Largest Herd in the State" unit. I have noticed that some of the true trophy units in NV, UT, NM target " on an average 15-25 bulls per 100 cows, but these bulls are 4.5 (avg) years and old, maybe even 5.5-6.5 years old. I think CO goes for the larger herd numbers, duh. So there will be 25-35 bulls per 100 cows, but younger/lesser bulls. As long as there there habitat can support the numbers. JMO, don't shoot me if you don't agree!!! Hope I draw a Mountain Goat tag this year.

 

[CheyenneElk]

Great information and a great subject. As a bow hunter, I prefer the 20-25+ bull:cow ratio for one reason...more competition for the cows. The greater the competition, the better likelihood of vocal elk as they compete for breeding rights. The more they compete with eachother, the better my chances of putting one in the freezer.

 

[trophyhill]

Great information and a great subject. As a bow hunter, I prefer the 20-25+ bull:cow ratio for one reason...more competition for the cows. The greater the competition, the better likelihood of vocal elk as they compete for breeding rights. The more they compete with eachother, the better my chances of putting one in the freezer.

there's definitely some truth to this statement imho. in my short elk hunting career so far i have hunted units with high numbers of bulls and low numbers of bulls. the units with low numbers of bulls are the ultimate challenge because the bulls are silent. at least this has been my experience thus far.

 

[Vanish]

Ok, I'm going to be the guy that picks on your math here.

If you have a 20:100 bull to cow ratio, that is actually 1 in 6 chance of it being a bull. When computing the chance, you have to take the number of bulls divided by the number of total elk, not cows.

I only bring this up because the numbers might get twisted around if we keep referring to different parameters. I suggest everyone just stick with bull to cow ratio.


One thing I find curious, why are whitetail deer managed for 1:1 while elk are managed 1:5? Is that only where deer populations are at maximum and they are being managed for trophy quality?

 

[MichMan]

This caught my eye because we're looking at new units in Colorado right now for 2012.

Trophyhill - what reason did the official you talked to have for the target ratio? Based on the numbers you posted from the different people, it sounds like 18-23 would be enough to keep the population going, so I would have to guess the number had more to do with the number of hunters Colorado wants in those units rather than the number of elk. I'd like to know what a biologist thinks or knows on the topic. Have you asked Chris Roe? He'd probably know.

Mich

 

[SouthernWyo]

Actually, it could be argued that numbers as low as 5 or fewer bulls per 100 cows are enough to "keep the population gowing" or even growing. Bull/cow ratios tend to say more about the ease of finding bulls (or lack thereof) and the overall "quality" or age class of the bulls that you can expect to see.

Cow/calf ratios tell more about the overall health of a herd, whether it's trend is stable, growing, or declining.