Science of the Seasons: Keep a hawk eye out for avian acrobatics

By Dr. David Wartinbee, for the Redoubt Reporter

A few weeks back, when the Redpolls were emptying our bird feeders every day, we had a special visitor. Out of the corner of my eye a large dark bird swept low over the ground and headed to an area below one of the feeders.

The feasting Redpolls seemed to scatter in every possible direction and just as fast, the predator was gone. I wondered what had just cruised by and suspected it might have been a goshawk. We have seen goshawks attempt to take small birds at the feeders in the past but this hawk was more dark brown than the characteristic blue-gray back and light-colored chest of adult goshawks.

I started looking out every window of the house in hopes that it might have landed nearby. Sure enough, there was the predator, perched in a tree staring at the bird feeder and the dozens of Redpolls that were back on the ground. It was a goshawk-sized bird with a dark brown back and a speckled front. The eyes were bright yellow and not the ruby red I expected of an adult goshawk. After a quick check in my bird book, I was certain that this was a juvenile goshawk.

Northern goshawks, perhaps better known simply as goshawks, are categorized as an accipiter and are found throughout North America, Europe and parts of Asia. They are a year-round predator here in Alaska but are so secretive that they are only occasionally seen. This past winter I encountered several goshawks but in almost every case, they were quickly out of sight and lost in thick woods.

I was usually able to identify them by their size, gray color and characteristic flight pattern of flap, flap, glide. Additionally, they are one of only a very few hawks that are seen here in winter months. These distinctions work in the winter, but in summer sharp-shined hawks frequently use that same flying cadence and Harlen’s hawks are similarly colored to immature goshawks.

Goshawks feed on a wide variety of possible prey. For example, they are comfortable hunting small mammals like squirrels, voles and weasels, but will also tackle mammals as large as adult varying hares. Additionally, they are well-equipped to take a large range of birds.

They will often take grouse or ptarmigan either when sitting on the ground or flying. Goshawks are capable of capturing a variety of shorebirds, small gulls, ducks and even smaller species of geese. They also will take passerine like those visiting my feeder last week. To further demonstrate the wide diversity of their potential prey, they are known to be predators on young owls and other birds of prey.

Their long tails and short, broad wings enable them to be very maneuverable while hunting in heavy woods. When chasing flying birds, they can reach almost 40 mph. Their speed and maneuvering ability are probably why goshawks are so popular with falconers. These flying skills enable them to successfully take flying ducks out of the air or rabbits running across the field.

Years back I was able to watch an adult goshawk chasing a pigeon next to Poppy Lane. The pigeon was diving and turning as fast as possible but the goshawk was able to match each direction change. The chase went on for what seemed to be several minutes when the pigeon dove into some heavy brush under a fence post.

The goshawk landed on the fence post and both birds seemed to need a rest. They restarted the chase when the pigeon took off again. This time the pigeon flew through some tight telephone wires and the goshawk had to swing wide.

With a slight advantage now, the pigeon headed for some nearby wooded cover. The goshawk was able to alternate dropping one wing and then another as it dodged between the tree trunks and quickly caught up.

The last I saw of the pair was the goshawk in hot pursuit of the pigeon just above the treetops. I don’t know who won out that day but they surely put on an amazing aerial display.

There is sexual dimorphism in goshawks with the females being larger and heavier than males. Females can stand up to 27 inches tall while males rarely reach more than 22 inches. Males have a wingspan just over 3 feet wide while females often have a wingspan of over 4 feet.

Both adults are similarly colored with blue-gray backs and wings with light, gray-striped fronts. But, as I learned when seeing the juvenile last week, immature goshawks are more of a nondescript brown.

Goshawks are starting to nest right now and are notorious defenders of their brood. Several young in the nest is the norm and both parents hunt extensively to feed their growing young.

They will continue to feed their young several weeks after they have left the nest. Then adults allow the young to remain in their established territory until they become sexually mature.

Because of the large numbers of varying hares our area has experienced in the past couple years, I am betting that the number of goshawks has also risen. I’ve certainly seen more in the past two years than in the previous 10. Keep a look out when you are in wooded areas for a quickly disappearing hawk flying quickly through the trees. You might have caught a glimpse of a goshawk.

David Wartinbee, Ph.D, J.D., is a biology professor at Kenai Peninsula College’s Kenai River Campus.

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