Adult female Northern Harrier with a marsh bird.
In mid-August to mid-September southbound migrant flocks of warblers (27 species) and vireos (4 species) “pile-up” in the forests and marshes along the north shore of Lake Huron in Michigan’s Eastern Upper Peninsula (EUP). In the beginning of September to about mid-October, they are joined by other songbirds – especially sparrows and Kinglets. Usually, at about 1 week into September, the hawks that prey upon songbirds have successfully raised their young and taught them how to hunt. Many of these hawks, including local nesting birds and migrants from further north, typically spend many days hunting within the habitats close to the northern Lake Huron shore.
A bounty of songbirds awaits them and more songbirds periodically arrive with north winds. During this time most of the warblers are juveniles because they migrate south later than the adults. They are not as experienced at dealing with the gauntlet of hawks that await, and many are easily captured.
This is a cruel fact of nature that plays out every year at my doorstep on a peninsula along northern Lake Huron. But it is part of the balance of nature on display. If no predators kept songbird populations in check certain forests could be depleted of insects, and a resulting crash of songbird populations could result.
Adult Merlin veering against a strong wind.
A Merlin’s diet consists of about 80% small birds. They nest along the northern Lake Huron shoreline at what seems like regular intervals. They are by far the most visible predator attacking songbirds on my peninsula, most often hunting the forest edge or clearings. At a forest/marsh edge I often witness a local nesting pair teaching their young to hunt the migrant flocks in early September.
Adult Merlin rising to a perch.
Adult Sharp-shinned hawk soaring.
Sharp-shinned hawks hunt mainly small birds within forests and are capable of very quick maneuvers during their sudden attacks.
Juvenile Sharp-shinned Hawk with a full crop.
The crop is a throat pouch used to temporarily store food – a successfully caught small bird or 2. Note the yellow eyes of this immature bird as compared to the adult’s red eyes.
Adult female Northern Harrier hunting low over the marsh at Pt. LaBarb – near the Mackinac Bridge in the U.P. Northern harriers seem to always hunt low and on the fly, often with a moth-like flight, sometimes remaining stationary into a strong enough wind before the attack at ground level. Their diet is much more varied than the Merlin’s or Sharp-shin’s but an unsuspecting sparrow or shorebird is always on the menu. This bird habitually circled the marsh. I just set-up my photo equipment and waited for it to make another circle.
Adult female Northern Harrier soaring in a strong wind. This type of image, with tail flared, usually happens when the wind is in the face of the photographer and the hawk flies away, but then turns quickly. Anticipation is required to nail the shot.
Broad-winged Hawk perched.
This species can often be seen in early September anywhere within a few miles of the shoreline, hunting roadside ditches from a perch. It is carnivorous but its diet is varied and changes with the seasons. An unwary bird at ground level is a welcome meal. This one looked at me in my van as if I was on the menu.