Can you judge the size in relation to a crow? What kind of varmits are they eating?

Hawks don't live in houses. They build stick nests in trees.

Hello-

The Hawk's are red-tails and are about the size of a large crow. I have never had the pleasure of seeing one in action but other family members have. I do know that there are mice, moles, voles, gophers, and snakes in the vineyard so that's probably what they're after. There's been quite a bit of spring work in the vineyard lately and it stirs up the critters so the hawks have been busy too. ~SF

If these are red-tails, they are a good bit larger than crows.

No, there is no box or nest you can provide for these birds. In fact, they never even spend a night in such, except when females are incubating eggs on their open nests.

Now for the "bad" news. There is no doubt that the birds are eating rodents in your vineyard. But their effect on rodent populations there is essentially nil. A red-tailed hawk consumes approximately 3-5 voles each day. At the best, the pair would be consuming ten voles each day from your vineyard. Unfortunately, there may be as many as two hundred voles or more per acre. And voles reproduce within a month after birth, brining on another litter of 4-8 little ones.

Therefore, as much as you'd like to think that the hawks are helping to control the mouse or vole populations in the vineyard, they aren't. In most cases, any vole eaten by a hawk merely creates an ecological "hole" that then can be filled by a maturing new young vole.

Secondly, your hawks will not spend all of their hours hunting only in your vineyard. If they did, they would go very hungry when the vole population crashes, as it does rather spontaneously every year or two. You can't presume that the pair is removing 10 voles each day from the vineyard. It's probably more like three or four.

This bit of ecological misinformation, that hawks control rodent populations, has been used for decades as a reason to protect hawks. It's in error. Hawks don't control rodent populations, as there are always far more rodents than the hawks can possibly eat within the hawk pair's large territory. Hawks should be (and are) protected just because they are fine specimens on their own, rodents notwithstanding.

--John Blakeman

OK, thanks for the info. Good thing we don't have a rodent problem...if we did though the 8 "vineyard" cats would sure help out too. Thanks again!

What about building a platform..would that work?

John, Hawks and predators do help keep poulations in check. Certain owl species such as a pair of snowy owls can consume as many as 3000 lemmings, and voles over a 4 month span during nesting. Red tailed hawks need to consume large amounts of small mammals in order to survive. So the impact of predators such as Red Tailed Hawks is not negligible, especially not in farmers fields.
Nathan

Nathan,

It is neglible. You must always include two factors other than the gross numbers eaten by the raptors. The first factor is the range or territory the raptors hunt in. If it's just 100 acres, the removal of 3000 rodents can be suppressive of rodent numbers. But if hunting occurs (as it does for larger raptors) over many square miles, the removal of a few thousand mice, voles, or lemmings is only a small fraction of the entire population of the large hunting area.

The second factor, totally unaccounted for in popular characterizations of the effects of raptors on prey populations, is the ability of rodents to reproduce, especially after loss to predators. Yes, 3000 lemmings (or voles or mice, or whatever) sounds like a lot of animals. It is. But how long does it take for the rodents to replace an individual lost to a raptor? Since rodents reproduce in just weeks, and in great numbers, the effects of owl or hawk predation is essentially nil. In fact, population ecology strongly suggests that raptor predation of rodents merely opens new, isolated "holes," places where a few hundred square feet have no mouse or vole because a hawk grabbed the one that lived there. (Yes, I know, they live socially, but the effects are the same.) Raptor predation merely creates opennings for copius numbers of young rodents to fill. In short, rodents reproduce faster than hawks can kill them.

If rodents produced only a single brood or two each year, raptors could, indeed, "control" them. But they don't. They breed time after time, producing multiple offspring each time. And because all raptors have large hunting ranges, they simply can't control small rodent populations. It was a nice way to get people to believe that hawks should be protected because they controlled mice and rats that eat human food. But authentic understanding of both the hunting frequencies and ranges of hawks, compared to the massive reproductive capacities of rodents (the neglected factor), show that hawks can't possibly "control" rodent populations in any effective way. There are too many mice, voles, rats, and lemmings, and worse yet, the little blighters simply reproduce too fast for a local pair of raptors to keep up.

And by the way, I've done extensive food consumption research on the food requirments of red-tailed hawks. They do not require "large amounts of small mammals in order to survive." They actually require about 125 grams of flesh each day. That's four or five voles. At the maximum (5 voles x 2 hawks x 365 days), a pair of red-tails can consume 3650 voles a year. Most red-tails have hunting ranges of 2 or more square miles. There is no way the removal of a mere 3650 voles from a two-mile square area could even be detected. There will be tens of thousands of voles left un-hunted, all of which are producing new broods of voles every 4-6 weeks or less for most of the year.

John,
I do understand what you are saying, that is there are far too many rodents reproducing far too quickly for birds of prey to keep them in check. Although I would be inclined to agree with you that disease and starvation would be much more limiting to the population than these raptors, in some cases they do have a considerable influence on the prey species. One excellent example of this would be island settings such as Amherst Island which has a large density of voles, and also a large concentration of raptors wanting to feed on them. When you get many snowy owls, great grays, boreals, Redtailed hawks, northern harriers, Northern Hawk owls, Rough Legged hawks, and Short and long eared owls all concentrated in one area, the result can be more than negligible. I would agree that one pair of red tailed hawks is not obviosuly going to have a massive influence over prey species, but there are certain circumstances John where they can.
Nathan

To encourage them to hang around, make sure there are tall poles to sit on and watch for prey.

Nathan,

For island habitats, especially during winter outbreaks of northern hawks and owls, a concentration of raptors can, indeed, significantly reduce rodent populations. But this occurs only in "island" habitats, either on real maritime islands, or in small "islands" of open habitat within massive forests.

But in each of these cases, both the raptor and prey populations are unsustainably high, concentrated in a specific locality because of an episodic occurance of high prey species. This is only a passing event in an isolated (and unrepresentative) local habitat.

The definitive criterion is how many raptors successfully nest in these areas. What is the nesting population of raptors on Amherst Island? How does it compare to equal areas on the mainland?

Yes, during migration or in winter, unusual numbers of raptors can be drawn to local areas with high prey populations. And in such cases, the concentrated raptor populations can deplete local mouse and vole populations. But then the raptors will depart for lack of food, and the rodents will grow back in normal numbers. This situation is isolated, local, and episodic. It is not representative of what happens over the massive ranges of any raptor. Except in isolated local anomolies, such as on islands from time to time, raptors don't (can't) "control" rodent populations. To say so, as so many otherwise good conservationists have done so for decades, is a biological fiction.

The nesting population has nothing to do with Amherst Island's raptor population, it is the large concentration of voles which draws these birds of prey. Have you not heard of Amherst before? It is hardly a passing event, as this locale can annually grab the continents high tally for snowy owls and many other raptor species. I would be inclined to agree with you that in the majority of cases, raptors alone cannot hope to control the rodent population. However, raptors coupled with other predators can in certain circumstances help limit these supposed "vermin" populations.
Nathan