April ushers in many returning birds, including the charismatic osprey. This large raptor makes massive stick nests – typically in the vicinity of a body of water, either fresh or salt – that are easily visible and earn special admiration from anyone willing to watch a bird with such a fascinating natural history, especially in regard to nesting. With a recent smattering of questions about their return, as well as nests lost to storms and humans, I wanted to address the full spectrum of osprey nesting.

First, we need to acknowledge the incredible movements that these birds have undertaken. To only reference them as ‘recently returning’ is selling them far too short. While we don’t know exactly where Maine’s ospreys go, there has been more research on ospreys that nest in other parts of New England. Thanks to GPS trackers on individual birds, we can see the paths they take and areas they frequent, often with hour-by-hour accuracy (depending on the tracking device). In the fall, several individuals from Massachusetts have been tracked moving down the East coast of the U.S., then island-hopping across the Caribbean, favoring a path through Cuba and Hispaniola. From there, they make the 400-plus-mile, open-water crossing over the Caribbean Sea before settling into areas from Venezuela through northern Brazil for the winter. This remarkable journey of about 3,000 miles is usually completed in less than three weeks. Even more noteworthy is their spring migration; their route, typically identical but in reverse, can be completed in less than two weeks, the prospects of breeding being a good motivator.

Now that the ospreys are back in Maine, they’ll be returning to sites where they have nested before, a behavior known as having “high site fidelity.” Nests are reused but can be built in one season, with males doing most of the work gathering material and females doing the finer construction and arrangement. One of the coolest things about ospreys is the way they plan for the future: some, especially ones that have a failed nest in one summer, will begin building an alternate nest that can be used in future years. Animal intelligence always seems to surprise us once we know how to measure it. Only recently have we been able to document animals’ perception of time and ability to plan for the future or recall past events, called the mental time travel hypothesis.

This sets the scene for the question we get the most: What do ospreys do when they return and their nest is gone? The quick answer, as you can probably guess now, is they rebuild, find a new spot to build, or move to the auxiliary nest they started last year. It is common for nests to get destroyed naturally, from high winds or heavy snow (we’ve all experienced that recently!). Readers in the greater Portland area may recall the long-present Fore River nest on a piling just across from Northern Light Mercy Hospital that was swept away by an astronomically high tide and strong winds.

We also receive a lot of inquiries from folks who observe nests that are removed by humans; worthy to note these are very few but often very public sites. This is where we’ll pause to acknowledge that ospreys, like all native birds in the U.S., are protected by the Migratory Bird Treaty Act (MBTA), which prohibits the “hunting, taking, capture, killing, possession, sale, purchase, shipment, transportation, carriage, or export of any … bird, or any part, nest or egg.” Permits can be obtained to allow certain activities otherwise prohibited by the MBTA (for example, Maine Audubon has a special permit to possess mounted birds and feathers for educational purposes). Companies, especially those working with public utilities, can also apply for permits, which are reviewed by state and federal agencies, to remove nests if there are concerns about their location and problems with infrastructure.

Unfortunately telephone poles look like great nesting sites to ospreys – they are basically tall dead trees, after all – but such close proximity to electrical lines causes concerns for both the birds and the utilities. Any work to remove or relocate nests is done outside of the nesting season, as no active nests should be disturbed.

It is sometimes hard to find reason in some human-wildlife interactions, especially when it involves removal of a nesting site, but we can thank long-standing protections like the Migratory Bird Treaty Act for preventing this from happening, at least without agency review or facing penalties of violating federal law. It does give me some relief knowing how adaptable wildlife is. It’s also worth remembering that ospreys are incredibly resilient; like the bald eagle, ospreys made an amazing recovery in the post-DDT era with a rebounding population; there are now more than 2,000 nesting pairs in Maine.

Do you have a nature question for Doug? Email questions to ask@maineaudubon.org and visit maineaudubon.org to learn more about birding, native plants, and programs and events focusing on Maine wildlife and habitat. Doug and other naturalists lead free bird walks on Thursday mornings, 7 to 9 a.m., at the Gilsland Farm Audubon Sanctuary in Falmouth.

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