Hog Island's nest cam overlooks Rachel and Steve, a pair of Ospreys now in their sixth year of nesting on the island. The webcam offers an intimate view of their private life and all its drama, including fighting off nest predators and nurturing young chicks. And even though it's billed as an Osprey cam, occasionally other species stop by for their 15 minutes of fame.
Windows on Wildlife: Hog Island's Nature Intervention Policy and 2019 Deterrence Plan
Now that ospreys Rachel and Steve have returned to their Hog Island nest, the Explore.org cameras are providing osprey enthusiasts with amazing views of their day-to-day life. Like most Explore.org nest cams, the primary purpose of the osprey cams, at both our Hog Island and Boat House nests, is to provide viewers with an enthralling and entertaining “Window on Wildlife” experience that enlightens viewers about osprey family life. Nest cams help us to connect with nature at an amazingly intimate level with wildlife, glimpsing the most detailed moments of their lives. They also help to reveal new osprey behaviors and details about the kinds and amounts of fish required to raise chicks. These discoveries are becoming increasingly important in light of the rapid changes in climate and fish populations.
Those that have watched osprey nests previously know that that they also show high drama from predatory eagles and owls as other surprises at the nest that can threaten the chicks and parents. The question naturally follows: When is it appropriate to intervene to reduce the risk of chick predation or other threatening events? I hope that the thoughts that follow will help to explain what Audubon is prepared to do under some of the situations that might occur.
Because the Audubon osprey nests are built on platforms on or near buildings, the nesting situation is an artificial setting. Therefore we feel some human effort to help these ospreys succeed in rearing young is appropriate. For example, we believe it is OK to deter predators from taking osprey chicks, but not to harm, capture, or remove predators. Hog Island is a sanctuary for all wildlife, including eagles and owls, both of which are likely to be nesting on the island with young of their own to feed. We believe that predators are neither good nor bad, right or wrong, but simply doing what they and their ancestors have done for eons--working hard for their next meal. Learning about eagles and owls, and how ospreys have adapted to live with them, are vital lessons from the osprey cams.
For example, we see that defense of the nest is a central feature of the division of parental responsibilities. This did not come to happen overnight, but evolved in response to predation. We see this in the behavior of the parents--osprey Steve spends much of his summer patrolling the skies near his nest. He perches nearby, watching vigilantly, and chases predators such as eagles and ravens from the vicinity. Through the cam, we have also seen osprey behavior change in response to predation. For example, Rachael modified her nighttime behavior from perching far from the chicks to sitting right on the nest cup. It will be interesting to see if she returns to this pattern this summer, which would suggest she remembers previous attacks.
In previous years, we have put metal sheathing around the Hog Island nest pole to deter raccoons from climbing into the nest. Last summer we also used a “teenager” mannequin and spotlights to provide additional deterrence. These methods appear to have helped and we plan to continue their use in 2019 (details below).
We also believe intervention is appropriate if an osprey chick or adult becomes entangled in plastic or fishing line, because these are human-created threats. We would attempt to remove the entangling material where possible, but only when it is safe for the birds and our staff. Likewise, if a chick falls or jumps from a nest, managers would attempt to replace the chick in the nest or place it in a nearby location for the parents to attend if the nest is at high risk from stinging insects. We would do the same for any other nestling bird. As a last resort, we might take an injured chick or fledgling to an avian rehabilitation center. However, we would not use pesticides to reduce the stinging insects because, like predators, these are naturally occurring environmental challenges to ospreys and pesticides can be toxic to birds. We also would not provide supplemental feedings at these nests. We will assess new situations as they arise on a case-by-case approach, usually favoring a “hands-off” approach.
Predator Deterrence Plan for 2019
In summer 2019, our predator deterrence plan will likely include the use of spotlights to illuminate the Hog Island osprey nest, and human-like mannequins placed near the Hog Island nest. The single human mannequin used in 2018 appeared to deter Great Horned Owls. Based on this, we may display as many as three mannequins near the nest in 2019. We will seek to change the mannequins’ clothing, modify their postures, and change their location often to reduce the likelihood of predators habituating to their presence. We will not display the mannequins until mid-July when Rachel begins leaving the chicks exposed at night, and we plan to keep them in place until after the chicks have fledged. This is the period when owls and eagles pose the greatest risk to osprey chicks.
In addition, we are considering building a new osprey nest platform atop nearby Porthole Lodge on Hog Island. This location is near Rachel and Steve’s existing nest, but further away from trees--an advantage that makes this nest site safer from predators. A nest platform in this site has a good chance of attracting another pair of ospreys, which could assist in defending the general area from predators. Or it might become a future nest site for Rachel and Steve. Some will recall that Steve was building a new nest on the Crown Royal, a fishing ship that was anchored nearby, until the owner moved it in 2018.
We hope readers find this rationale helpful both upfront and as the season proceeds--especially if predation attempts occur at these osprey nests. Meanwhile, we look forward to another season of osprey watching with you!
National Audubon Society, Executive Director of the Seabird Restoration Program and Vice president for Bird Conservation