When I sat down and put finger to keyboard (pen to paper for you older folks!), I planned to write about how birds in general find each other to get ready to migrate, but I think I’ll leave that for another day and just focus on one species for now. I have always wondered how thousands of Broad-winged Hawks can find each other so they can migrate in huge flocks. You may recall, in the past I have talked about these kettles of hawks that are moving through North Durham and the Kawarthas right now. The other day almost 1,000 moved through Whitby in just four hours and later that day over 3,400 flew through Oshawa! So, let’s explore the life of the Broad-winged Hawk a bit and see if we can answer the question – how do they find each other during migration? The Broad-wing is a hawk that favours heavily forested deciduous or mixed woods, such as we find through much of this area. In fact, they nest right beside my house in Scugog Township. The nest is high in a tree close to the trunk and well-concealed. The four young are demanding, and need lots of food to survive. So the male, which does much of the hunting, brings food to the female which feeds the young a variety of prey, including small birds, mammals, amphibians, large insects and even snakes. The primary diet in our area seems to be chipmunks, amphibians and short-tailed shrews, but any tasty snack will do. Okay flash forward to the fall migration. Unlike most hawks who migrate through, over a protracted period of time, the Broad-wings seems to be rushing to get out of here with the vast majority leaving in just a two week period. Compare this to the Sharp-shinned Hawk which can migrate anywhere from late August to early December. The impetus for the Broad-wing to leave is sparked by a number of factors, but it is believed that the diminished availability of prey is the key reason they leave so early and so quickly. So, once early September arrives and the days get shorter, they start to move towards the shore of Lake Ontario where they rest and feed for a few days. Suddenly the conditions become perfect; bright sunny days with few clouds and excellent thermals to provide lift, coupled with a light wind from the north, and so, off they go. As they travel they encounter more and more of their kind to form the large flocks I mentioned above. These flocks get bigger and bigger, until they number in the tens of thousands, as they move southwest through Central America. A ‘river’ of hawks can be experienced in Panama, as the Broad-wings join Mississippi Kites and Swainson’s Hawks in migration. It is here you might see 500,000 hawks in a day! They keep flying south, with the young birds dropping off first and the males last, as they occupy a large range, reaching from Panama south into Brazil and Peru. Ironically, when nesting, they are solitary and rarely would you find more than one pair in a woodlot. This is of course in contrast to the huge numbers which move together over a period of weeks, flying, feeding and then roosting together until they get to their wintering grounds, where they become solitary once again. On their wintering grounds, they occupy a territory of only about a square mile. Okay coming back to the question – how do they find each other? Short answer is, it’s opportunistic. They all are compelled to leave over a short period of time, all head to the shores of the Great Lakes to get ready to migrate, and all leave when the conditions are perfect. Then they head west and then southwest, en masse, to Central America on their way to South America. Couple this with an abundance of migrating small birds and large insects, such as Green Darners (a dragonfly), and you create the perfect mix of food and opportunity. Geoff Carpentier is a published author, expedition guide and environmental consultant. Visit Geoff on-line at www.avocetnatureservices.com and on LinkedIn and Facebook.