Montana Best Times: Big Sky Birding Column

The Pros and Cons of Osprey Nest Platforms -- What Every Wildlife Enthusiast and Angler Needs to Know (July 2005)

First of all, in order to proceed with a discussion about osprey nest platforms, it is important to realize ospreys are primarily fish predators. They differ from Bald Eagles in that they capture prey that is considerably smaller on average than fish caught by Bald Eagles. Ospreys typically catch fish that measure 4-14 inches, whereas Bald Eagles can reliably catch and haul off larger fish that can vary anywhere from 10-22 inches. Also ospreys are very efficient at what they do, and can make a sizeable dent on fish populations particularly in rivers or streams if the nesting density becomes supersaturated. After all one must remember, if fishes are abundant in an area, the limiting factor for ospreys is almost always the availability of nest sites. Once ample nest sites are available, the sky is the limit on how many fish they can kill.

Don't let anyone fool you, ospreys are non-selective as to the types of fishes they catch. It doesn't matter if it is a trout, a perch, a whitefish, walleye, etc., ospreys are capable of catching many fishes as long as they are the right size. If your goal is to have many different age classes of fish around, you may want to reconsider putting up an osprey nest platform on your property.

For those people that are convinced an osprey nest platform is a perfect fit for their property, here are some pointers to consider:

• Try placing the nest platform on a high quality utility style pole ( 40+ feet)
• Do not place the nest platform too close to human habitation. Ospreys do not like being constantly disturbed during egg laying and chick rearing. The nest platform needs to be atleast 100 yards from the nearest house, but the greater the distance you can provide the better. Also if you have pets running around it may not work for you.
• It is important to realize that nesting ospreys have to shade (with their wings) and protect the eggs and small young, from the elements and avian predators such as ravens. So selecting an area that is disturbance-free is critical.
• Osprey nest platforms if not placed properly, can turn out to be Canada Goose nest platform, since geese usually arrive earlier than ospreys in the spring and geese can quickly take over an abandoned or failed osprey nest.
• If there is a great deal of boat traffic or human disturbance, you might want to consider placing the nest further inland or set back from the shore to ensure the nest platform will be protected from disturbance.
• Ospreys lay 1-3 eggs, with two eggs being average; incubation lasts 38 days and mainly is performed by the female; fledging takes 51-54 days after hatching; and they only produce 1 brood per year.
• For best results, sticks should be placed and arranged in the nest platform during installation. Having perches near the nest is helpful, but not necessary.

Enjoy! And the Best of Big Sky Birding to you!