At Featherstone, we are responsible for our vines from the ground to the air. In order to limit the damage that nuisance birds like starlings and robins cause to our grape crop, co-owner Louise Engel flies a Harris hawk in the vineyard. What follows is her story.
I am going to address briefly how I use a raptor to control bird damage in our vinifera grapes. My first season doing this was the summer of 2004. I don't do this as a profession and anyone reading this who is looking for professional bird control is advised to contact Dan Frankian at www.hawkeye.ca.
We notice two types of pest birds -- flock birds and resident birds.
Flock birds: We don't have any major hydro lines or a marsh to provide overnight resting but we notice flocks of migrating birds -- mostly starlings -- heading south to corn & soybean fields at sunrise and sunset. They flow by in a stream and often they stop for a meal.
Resident: We have resident robin populations. We border light woods on our west, which harbours the robins. They take fruit but they also damage fruit and leave it. Damaged fruit is actually worse than 'no fruit' because the damaged grapes attract fruit flies and this, in turn, encourages rot.
Bird Pressure: Birds exert a pressure on grapes -- just like mildew and mould do.
Both mildew and bird pressure can be treated, contained and controlled to a certain extent. Birds, like mildew, represent a potential threat that could be a huge influence on the grape crop if left unchecked. However, birds could also be a minimal influence, depending on the year and how well we control them. We have found bird pressure to be seasonal and some years are worse than others.
We try not to let birds settle in. Once we have a resident population, others are attracted. We use:
We have resident pest birds - birds living within a 1 km range -- like starlings and robins.
Any one of these control strategies alone is not completely effective. Some work better in certain years but all of them in combination are very effective. I will be addressing the last one -- raptor use.
Falconry is the taking of wild quarry in its natural state and habitat, using trained birds of prey. Birds of prey are known as raptors. The root comes from "rapacious" and describes their living on captured prey. Raptors include eagles, hawks (accipiters, buteos), falcons, owls, kites and harriers. Falconry has a long tradition in the Middle and Far East and a shorter history in Europe. In the U.S.A. there are approx. 5,000 active falconers and in Ontario there are about 120 that are licensed.
In 2005 I completed a two-year apprenticeship program and am a licensed falconer. I fly a Harris' Hawk (parabuteo) and I do this as a hobby. I do not do professional bird control and do not fly my hawk other than on my own farm. (If you would like professional bird control, talk to Dan Frankian at www.hawkeye.ca)
Harris' Hawks are native to Central and South America and their range extends as far north as Mexico, Arizona and Texas. Most raptorial birds hunt individually. Co-operative hunting, even among mated pairs in other species, is unusual. Harris hawks, alone
among raptors, engage in co-operative hunting as they hunt not merely in pairs, but in social groups in much the same manner as a pack of wolves. Thus Harris' Hawks are naturally pre-disposed to co-operative hunting with a human partner. Harris hawks will fly on a wide variety of quarry -- rabbits, pheasants, waterfowl, crows, starlings -- making them very popular with falconers.
I fly a male Harris' Hawk named Amadeus. In raptors, the males are usually about one third lighter than the females and my preference was to purchase a relatively small male since they are faster and more agile in the air. Smaller = faster in the bird world. Songbirds being an example of how smaller birds are quick and agile.
The vast majority of Harris' hawkers hunt rabbits. However, I hunt only starlings with my Harris. He catches and eats starlings, and whether he takes them in the air or on the ground, he eats them entirely. He plucks the main feathers and then eats bones, cartilage, smaller feathers, everything.
Hawks don't drink much water (unlike chickens for example) so his food is his main source of moisture intake. Starlings are light enough that he can carry them and he usually takes them to a place where he has cover -- bushes, shrubs, etc. He mantles his food while he eats, covering it with his wings so other raptors can't see it and steal it.
Hawks don't share. It takes him about 15 min to eat a starling. Once he has eaten his crop swells visibly and after 12-18 hours he will cast up the feather and bone portion that he is unable to digest. Starlings are small enough (about 80 gm) that he can eat one a day but it is very natural for raptors to gorge three or four times a week and not eat much in between.
While he does catch nuisance starlings, it is his daily presence in the vineyard that is the largest deterrent to both flock and resident birds.
Training a bird of prey requires time and patience. The only modification to its wild behavior is that the bird now allows a specific human being to approach it on its quarry. The birds remain wild and are capable of returning to the wild at any time they are flown.
Birds of prey are trained entirely by reward. The bird's natural response to food is the key and no punishment is ever used, nor would it be effective. While dogs will respond to a tone of voice, raptors have no desire to please their owners. Raptors are not pets and a part of every raptor remains forever aloof, reserved and wild.
Training in falconry involves having the hawk learn to accept a person as an aid to more successful hunting and to a more dependable food supply. The bird's owner provides a carefully measured diet designed to keep the bird at its optimum flying weight. Too heavy, the bird is inclined towards lethargy and independence. Too light, and the bird is weak and unhealthy. He returns to my glove because he is hungry and perceives me as a source of food. A working raptor is weighed every day on a gram scale. A daily log is kept daily of his weight, food intake and the outside temperature and weather (since this affects how much food he needs).
There is an initial training period during which the bird learns to associate the owner's leather glove with food. The bird learns to fly to the glove from increasingly large distances. Outdoor flying is first done on a long 'leash' called a creance. Doing this reliably can take a few days or a few weeks. Once you can do this with confidence, the Big Day comes and the bird flies free.
In the summer I free fly Amadeus for a couple of hours a day, often getting up early to catch starlings as they passed through. I walk through the vineyard rousing anything I can, Amadeus following from fencepost to fencepost.
He can be outside free flying anytime I am out but I don't leave him out for hours at a time unsupervised. He is often out on patrol while I am crop thinning, gardening or doing any outdoor work. His presence, whether he is catching anything or not, serves as a noticeable deterrent to smaller birds.
Sometimes raptors that are being used for bird control are tethered to their perches in various parts of an orchard. I prefer not to do this due to concerns about his safety (dogs, other raptors, theft).
Well, it certainly helps, especially when used in conjunction with other bird control devices. Certainly by the end of the growing season I run out of starlings to fly on and taking Amadeus out can get a little boring. If it works, I believe that it is because he is resident and is flown every day in a relatively small vineyard.