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Cooter

Grouse cycle - again

11 posts in this topic

Thought I saw this topic twitch again so it may need another beating. What I want to discuss is the causes for the cycle - why the ups and downs? Not so much at what point of the cycle last year or this year.

Curious about theories, old or new. Predator based? Forage based? Neither, both? Logging/habitat management? Other?

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yeah this is a weird topic, its too tough to know the real explanation? so i would also like to hear some of your thoughts also?

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I was told a theory from a wildlife biologist that the chemical make-up in aspen buds (grouse main food)goes through a up and down cycle. I can't remember the chemical, but it builds up over time in the aspen - high amounts of it start to make the aspen buds less palatable to grouse. When its at its highest, grouse will turn more to feeding on birch. The grouse pop may follow this cycle also. The biologist emphasized this was just a theory at this point.

Here in NE Minnesota we have plenty of good habitat due to forest management and logging - The habitat has improved for grouse over the last 30 years and yet we still have the pop swings so there may be something to this theory.

Anyways, cycle or not, this winter has got to be hard on grouse - not much snow since December has caused a hard crust on the snow. Several hard cold snaps (20-30 below with 30-50 below windchills)and the grouse have no snow to bury in for shelter - bummer!

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I have heard two different theories. The first is based off predation of hawks and how they relate to the population of snow hares? (or whatever rabbit is common up here). They will stay further north i.e. canada until population lowers of rabbits and then come south to MN and feed on grouse/rabbits until population is low and then go back north and so on equaling out to the famous 10 year cycle. The other is how the grouse relate to the army worms?? again not sure what there called, but the ones that come in the thousands. I forget the reasoning behind this one, but im sure someone else knows something about it and can tell more. And they go up and down because of popluation of worms...Not sure i believe either of them, but a couple reasons ive heard.

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I've heard the same thing bowfin has about the aspen buds becoming bitter and unpalatable for grouse. I heard it speculated that the aspens make the chemical change to deal with the tent caterpillars which also rise and fall on a cycle. The only thing I'm sure of is that no on knows for sure.

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The chemical is Tannin. And the Aspens do create it. And to me it is the best explanation going. The cycle is much less drastic in the south where the main food source is not Aspen buds.

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Read...

Walter J. Jakubas1, Gordon W. Gullion1 and Thomas P. Clausen2

(1) Department of Fisheries and Wildlife, University of Minnesota, 55108 St. Paul, Minnesota

(2) Department of Chemistry, University of Alaska, 99775 Fairbanks, Alaska

Received: 1 August 1988 Accepted: 20 September 1988

Abstract Quaking aspen (Populus tremuloides Michx.) staminate flower buds and the extended catkins are primary food resources for ruffed grouse (Bonasa umbellus). Winter feeding observations indicate that ruffed grouse select specific trees or clones of quaking aspen to feed in. Flower buds and catkins of quaking aspen were analyzed for secondary compounds (tannins, alkaloids, and phenolics) that might cause ruffed grouse to avoid trees with high levels of these compounds. Coniferyl benzoate, a compound that has not been previously found in quaking aspen, exists in significantly higher concentrations in buds from trees with no feeding history as compared to ruffed grouse feeding trees. Aspen catkins were also significantly lower in coniferyl benzoate than buds from the same tree. Ruffed grouse feeding preference was not related to the tannin or total phenolic levels found in buds or catkins. Buds from feeding trees had higher protein levels than trees with no feeding history; however, catkins did not differ from buds in protein concentration. The high use of extended catkins in the spring by ruffed grouse is probably due to a lower percentage of bud scale material in the catkin as opposed to the dormant bud. Bud scales contain almost all of the nontannin phenolics in catkins and dormant buds. A feeding strategy where bud scales are avoided may exist for other bird species that feed on quaking aspen. Dormant flower buds are significantly lower in protein-precipitable tannins than catkins and differ in secondary metabolite composition from other aspen foliage.

Key words Coniferyl benzoate - Populus tremuloides - Bonasa umbellus - Fringillidae - feeding behavior - secondary metabolites - tannins - phenols

Minnesota Agriculture Experiment Station Journal Series No. 16,953.

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Newer studies suggest that the feeding patterns stay the same, but the higher levels of tannins could cause damage to the eggs come spring.

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 Originally Posted By: Bowfin
I was told a theory from a wildlife biologist that the chemical make-up in aspen buds (grouse main food)goes through a up and down cycle. I can't remember the chemical, but it builds up over time in the aspen - high amounts of it start to make the aspen buds less palatable to grouse. When its at its highest, grouse will turn more to feeding on birch. The grouse pop may follow this cycle also. The biologist emphasized this was just a theory at this point.

Here in NE Minnesota we have plenty of good habitat due to forest management and logging - The habitat has improved for grouse over the last 30 years and yet we still have the pop swings so there may be something to this theory.

Anyways, cycle or not, this winter has got to be hard on grouse - not much snow since December has caused a hard crust on the snow. Several hard cold snaps (20-30 below with 30-50 below windchills)and the grouse have no snow to bury in for shelter - bummer!

there is plenty of snow and even with the crust, the snow in the woods is different. i have found the depressions were grouse have been in the snow. Barring a cold wet spring, they should do fine

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I think last winter was more of a hard winter than this year. One could not even snowmobile last year. This year it has been good.

As for the grouse cycle thing, you just have to find them. That is what I have found.

I got birds when I went out and posted images of them on here. I only went out 4-5 times and had success all but one time I tried an off set area.

Get out and find them, they are around no matter what year it is.

Good luck..

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Grouse cycle on approximate 10 year cycle (high to high), but year to year fluctuations do occur. Winter can impact.

Spring and early summers that are cool and rainy have a big impact on fall populations and hunter success.

Last peak was moderated (lowered) by three consecutive wet and cool springs. 1999 - 2001 could have been better than they were and they were great!

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