It’s in your nature: Osprey
Pennsylvania and North America have two raptors that feed on fish. They are the bald eagle and the osprey. The osprey numbers have increased throughout North America since the ban on the very damaging DDT. Since DDT levels have dropped, the ospreys are now successfully breeding and their numbers are rebounding. It was the osprey’s fish diet that was leading to their demise. DDT kept accumulating in fish, and for those birds that ate primarily fish, they had high levels of DDT. Levels so high that it affected their reproduction. In the case of ospreys, eagles and pelicans, it resulted in eggshells so thin they broke. Or, DDT resulted in infertile individuals.
Ospreys were never very common in Pennsylvania. By 1986 only one nest was identified in Pennsylvania. Today they nest in 20 different Pennsylvania counties. I am aware of one nest in Carbon County, and I believe Monroe County has a few more. On one of my few trips to Florida, I saw many nests, even in rather populated areas. Many chose power transmission towers, but communication towers seem to be favored areas for them there. In the Assateague Island area, south of Ocean City, Maryland, I’ve seen osprey nests on channel markers.
The osprey has a wingspan just shy of 6 feet and soars with a characteristic “M shaped” wing formation. When I took some of my junior high classes to Bake Oven Knob for hawk watching field trips, I would tell them to be aware of the “McDonald’s” sign wing pattern.
Ospreys are rather unique in two ways. They often hover over a potential meal, focusing on a fish below them. Kestrels and red-tailed hawks employ this approach as well. The other unique adaptation they have, along with owls, is a reversible outer talon. They can use two talons forward and back so they grasp and carry fish easier. The bottoms of their feet also have barbed pads for easier gripping of slippery fish.
Back in 1980, my college professor at ESSC, Dr. Larry Rymon, began a hacking project at lakes in the Poconos. Young osprey in areas where they were common were transported to hacking towers. Here, without seeing the humans feeding them, they matured and were released. This was successful and continued a number of years. Probably many of the Pocono nesting ospreys today are progeny of those “hacked” osprey.
Osprey feed by diving feet first into the water. After getting off the water surface they do a characteristic “shudder” to shed water. Then they align the fish headfirst for better flying efficiency. Where bald eagles live near them, the eagles often harass the osprey until it drops its prey, and the eagle’s thievery is complete. A few years ago, on a fall morning at Cape May, I watched an osprey dive into a pond, catch a fish, and within a minute an adult bald eagle began chasing it until the osprey gave up its meal. Just another small drama in nature.
Look for ospreys to begin migrating through our area about the third week of August, many on their way as far south as South America.
Test Your Outdoor Knowledge: Which of these birds eats smaller fish than the osprey? A. common merganser, B. belted kingfisher, C. common loon, D. all of these.
Last Week’s Trivia Answer: More than 300 bird species in North America migrate.
Contact Barry Reed at firstname.lastname@example.org.