How does winter effect the rut?

[IdahoRuss]

Curious to know how other people think about this topic, I make my living working on a cattle ranch in Idaho. The ranch I work for runs on some private and some forest service/BLM. The reason that's important in this discussion is to show the cattle I'm around are not being fed much for hay but instead they have to graze for there feed year round like our deer and elk herds.

The things I have noticed over the years is if the winter range is tough and drags into "spring" the high energy grasses don't start growing until later into the spring and the cows stay in poorer condition longer which also means it'll take more time and feed to pick here condition back up to where it needs to be for breeding season in let's say May-June time frame and if that cow doesn't pick back up she is less likely to come into heat and get bred until later in the breeding season.

My thoughts have been if our deer and elk herds struggle for a winter and maybe the spring has a slow start or our summer starts early and everything kind of drys off early will that mean the doe and cow groups will have a slower start on picking up there condition which in return could cause a later rutting season or maybe a less active rut in certain areas?

I know that they will come into heat eventually but for elk could a slow start in spring time be the cause of the October rut fests or when we have an easier winter and a wet productive spring will the elk rut start earlier in September?

I believe this has more effect on elk due to their earlier rut dates over deer so I don't know if this idea has too much to do with the November rut? Maybe a good feed year will get those does to start rutting that Oct 25th time frame?

Curious to know what the thought is on this, I think if people really start paying close attention to this then we can get a better ball park idea on when to expect rut behavior to start which could make for better planning a hunt.

 

[Customweld]

That's a really interesting question. If it affects cattle that are primarily on the range, surely you would think it would affect other ungulates as well. @robby denning , here's your next podcast topic!

 

[steelheadmike]

From what I have read, the vast majority of breeding occurs during at the same time of year, every year. The estrus cycle is a function of daylight hours. Environmental conditions may play a factor in some of the outliers but don't have much influence on most of the breeding activity.

RUT activity (bulls/bucks breaking off, chasing harems, etc) could be affected by environmental conditions, but, biologically, the estrus cycle is what really drives it. The October rutfests are probably bulls that are still full of testosterone but the vast majority of cows are done. You ever been outside a bar at 2:30am? Same thing.

 

[Mykolaivka887]

From what I have read, the vast majority of breeding occurs during at the same time of year, every year. The estrus cycle is a function of daylight hours. Environmental conditions may play a factor in some of the outliers but don't have much influence on most of the breeding activity.

This is scientifically accurate /\/\/\

 

[Poser]

The rut timing was determined during the last ice age when calves/fawns had to be born in a narrow 2 week window in order to be big enough/healthy enough to survive their first winter. That's only a little over 10,000 years ago which isn't much time o the evolutionary timeline. Very little has changed. The rut has the same timing every year, hunter's perceptions and experience of the rut are what change year to year.

 

[robby denning]

only guessing (and I apolgize for not thoroughly reading all the posts, it may have been answered but I'm on run)

but last year was a perfect year to test your theory, late spring, poor body condition but it seemed the rut came off on time for mule deer, i.e. late October into early Nov starting

In my experience, moon phase and weather (cold vs warm) has a bigger effect.

Poor body condition from range will affect body weight of the fawn/calf and in extreme conditions the mother may not carry to full term

@Customweld this would be a great question for Kevin Monteith for sure...

 

[canyonhunter47]

The biologists say that rut timing is determined by photoperiod (ie length of day), which is driven by date and by latitude. The exact photoperiod is determined by genetics but the goal of rut timing is to give the best chance of survival to fawns and calves when they drop in the summer.

Since there was a genetic bottleneck around the turn of the century when many of our deer and elk populations including whole subspecies were wiped out, the genetics/photoperiod/rut timing is probably not what it is supposed to be. Just look up rut timing in Alabama

I’m not an expert but my general observation is that environmental condition still have a pretty big effect on overall activity, which affects how we perceive the rut. For example, the coues deer rut in AZ is in January but on a good year, you’ll see a lot of prerut activity in the December season. Last year on the rifle tag I barely saw any rut/prerut activity and on a really bad year like 2020 we joked that the rut got cancelled

 

[steelheadmike]

This would be a good point to determine what want to talk about: The RUT or ESTRUS.

RUT activity can be highly variable and extend for some time before and after the main estrus cycle. Enviromental factors play a part but just because hunters aren't seeing the activity doesn't mean it's not happening.

ESTRUS, depending on location, occurs at the same time of year. It is controlled by photoperiod and is timed to correlate end of gestation/birth with the greatest abundance of food on the landscape the following year. I.e., in the mountain west the greatest food availability is usually around mid-June following snow melt, hence that's when calves/fawns drop. But, in Arizona, the greatest food availability is mid-August following the summer monsoon season so the estrus period is a couple months later than in more northern climates.

 

[canyonhunter47]

The October rutfests are probably bulls that are still full of testosterone but the vast majority of cows are done. You ever been outside a bar at 2:30am? Same thing.

I watched a young buck mount a doe on Labor Day, so I imagine males are ready to rock “just in case” a lot more than females are in estrus

 

[Bubblehide]

I'm going to tackle this from a slightly different direction consistent with Robby's poor body condition statement.

In species that are polyestrus, such as pigs, they are capable of cycling continuously. However, when conditions (body condition and environmental) are poor, cyclijg into estrus stops. It is believed to be a self-preservation function. Furthermore, if the conditions become poor during pregnancy, typically the pregnancy does not reach a live birth stage, i.e., still birth, or naturally aborted.

I believe these preservation functions are pretty much universal as a soecies survival function. Cervids appear simular, in that they likely will not cycle a 2nd time if not bread; and if conditions remain poor during pregnancy, body condition and poor environmental conditions will not support a viable pregnancy. So, I do believe there is any significant change in the timing of the rut, but rather a significant decline in fawn and calf production-recruitment.

 

[Poser]

I'm going to tackle this from a slightly different direction consistent with Robby's poor body condition statement.

In species that are polyestrus, such as pigs, they are capable of cycling continuously. However, when conditions (body condition and environmental) are poor, cyclijg into estrus stops. It is believed to be a self-preservation function. Furthermore, if the conditions become poor during pregnancy, typically the pregnancy does not reach a live birth stage, i.e., still birth, or naturally aborted.

I believe these preservation functions are pretty much universal as a soecies survival function. Cervids appear simular, in that they likely will not cycle a 2nd time if not bread; and if conditions remain poor during pregnancy, body condition and poor environmental conditions will not support a viable pregnancy. So, I do believe there is any significant change in the timing of the rut, but rather a significant decline in fawn and calf production-recruitment.

If you look at the data points coming out of the (Colorado) San Juans over the last few years, it does appear that pregnant calves with poor nutrition are failing to have successful births due to miscarriages.

 

[Bubblehide]

If you look at the data points coming out of the (Colorado) San Juans over the last few years, it does appear that pregnant calves with poor nutrition are failing to have successful births due to miscarriages.

I have not looked at that data, but I see it in the areas I frequent. It simply makes sense based on studies from other areas. It appears most of the west's herds are experiencing this.

 

[IdahoRuss]

From what I have read, the vast majority of breeding occurs during at the same time of year, every year. The estrus cycle is a function of daylight hours. Environmental conditions may play a factor in some of the outliers but don't have much influence on most of the breeding activity.

RUT activity (bulls/bucks breaking off, chasing harems, etc) could be affected by environmental conditions, but, biologically, the estrus cycle is what really drives it. The October rutfests are probably bulls that are still full of testosterone but the vast majority of cows are done. You ever been outside a bar at 2:30am? Same thing.

Yeah I do agree the breeding season generally starts around the same time frame year to year I was just thinking that maybe the environmental conditions help increase the number of cows that come into estrus earlier in that time frame instead of maybe being drug out through September

 

[willfrye027]

Yeah I do agree the breeding season generally starts around the same time frame year to year I was just thinking that maybe the environmental conditions help increase the number of cows that come into estrus earlier in that time frame instead of maybe being drug out through September

We have data on exactly when fawns are born in the spring, which is very consistent, and the gestation time does not fluctuate. So good data to suggest a very specific breeding time which does not vary. Plus extremely high rates of actual pregnancy regardless of the conditions.

But absolutely the range conditions affect the success of rearing that fawn..for now it seems the breeding itself is not flexible.


At least that’s what I’ve learned from the biologists