Osprey Adopt-A-Nest Program
Monitoring the reproductive success of nesting Osprey pairs in Michigan
The Osprey Adopt-A-Nest program is a community science initiative that utilizes interested volunteers to monitor osprey nests and track the reproductive success of nesting pairs throughout Michigan.
An Osprey observed in 2022 by Joan Bonin, an Adopt-A-Nest community scientist.
Many of the photos used throughout this StoryMap were taken by Adopt-A-Nest volunteers, without whom this survey effort would not be possible. We would like to thank all Adopt-A-Nest volunteers for making this possible and for supporting Osprey conservation.
What is an Osprey?
Ospreys (Pandion haliaetus) are large hawks with long, narrow wings, dark brown feathers above, and white feathers below. They have dark "wrist" patches on the underside of their wings that are visible during flight. Females may have dark streaks of color around their necks and are generally larger than males.
Osprey Calling at Nest (Mick Thompson, Flickr)
Diet
Osprey feed almost exclusively on fish and therefore prefer nesting sites that are above or near bodies of water such as rivers, lakes, reservoirs, swamps, and marshes.
Nesting Locations
Historically, Osprey only nested in trees, snags, or on cliffs, but they have adapted to man-made structures such as utility poles, towers, chimneys, windmills, buoys, and platforms.
Nests
Osprey pairs create nests that are made up of sticks and lined with bark, grasses, moss, lichen, or mud. The male generally collects most of the material and the female arranges the nest.
Pairs tend to return to the same nesting site each year, adding to it each time. Nests can reach 10-13 feet deep and 3-6 feet in diameter if a pair has returned and added to it for years. However, nests that are built on artificial platforms tend to be smaller.
Offspring
Female Osprey incubate one to four (usually three) eggs for 32-43 days, while the male delivers food to her at the nest. After hatching, the offspring fledge around 48-59 days of age.
Juvenile or Adult?
Osprey reach sexual maturity at three years of age. The feathers on the back of juvenile Osprey have white outlines, giving them a spotted appearance.
The History of Osprey in Michigan
Historically
Osprey were thought to nest throughout all of Michigan.
1940s
Indiscriminate shooting and contaminants (e.g. DDT, a synthetic insecticide) extirpated Osprey from the southern lower peninsula.
1972
Use of DDT was discontinued in the United States.
Post DDT-era
Osprey populations recovered well in the north, but not as well in southern Michigan.
Today
Although Osprey are now spreading into southern Michigan, there are still twice as many Ospreys in the northern lower peninsula and three times as many in the upper peninsula.
Why are Osprey Important?
Status
The Osprey is a species of special concern in Michigan. As stated above, they were nearly eradicated from Michigan via hunting and chemical contaminants in the mid-1900s.
Why Protect Osprey?
Ospreys are a valuable indicator species for monitoring the long-term health of large rivers and other water bodies. They are dependent on fish as their main source of food and are highly sensitive to contaminates. In addition, the nests that they build are utilized by several other species of birds.
They are very efficient hunters and can aid in the management of fish populations without the potential for over-fishing.
Surveying the reproductive success of Osprey nesting pairs gives us valuable insight into the current distribution and health of populations across Michigan. Data from these surveys can also be used to aid conservation efforts and teach us how to better aid Ospreys in their recovery from previous extirpation.
2022-2023 Nest Survey Effort Results
Between April 2022 and September 2023, 991 Osprey nest check surveys were conducted in 39 counties by Adopt-A-Nest community scientists. Using the map below, click on Michigan's counties to explore photos taken by observers and when the last Osprey sightings occurred in each county. Has your county been recently surveyed?
Osprey 2023 Survey Effort
Data Collected in Nest Check Surveys
Nest Activity
Of the 991 nest checks that were made during the 2022-2023 survey effort, 78% were of active nesting sites. Non-active nests made up 19% of observations and new nests made up only 3% of observations.
2022-2023 Osprey Survey Effort Nest Activity Data
Number of Young
Of the 991 nest checks, 313 were able to observe offspring at the nest. 44% of these observed 1 offspring, 47% observed 2 offspring, and 9% observed 3+ offspring.
Number of Young Observed in 2022-2023 Nest Check Surveys
Age of Young
Of those that contained young when surveyed, most nests contained fledglings (46%), followed closely behind by chicks (40%). There were very few reports of egg sightings (14%), but this is likely due to the challenges involved with viewing Osprey eggs in nests that are very high off of the ground.
Age of Offspring Observed in 2022-2023 Nest Check Surveys
Nest Location
64.9% of the nests that were observed were built in cell towers. In fact, over 97% of the observations made in this study effort viewed nests that were created on/in man-made structures. Other nest types included pole platforms, tripod platforms, electric poles, high tension towers, light poles, snags, grain silos, telephone poles, water towers, and railroad trestles.
Nest Types Observed in 2022-2023 Survey Effort
Nest Site Quality
Site quality surrounding nests was described as "excellent" in 42.8% of surveys and "good" in 28.9%. "Fair" and "poor" site qualities were only given for 10.9% of surveys.
Site Quality Descriptions Given in 2022-2023 Osprey Nest Surveys
How to Get Involved
Conducting a Survey
The best months to observe osprey nesting are spring through late summer, however the best time to observe Osprey in Michigan varies depending on your location:
Image of Osprey taken through binoculars by V. Rousr, an Adopt-A-Nest community scientist.
- Northern Michigan: June-August
- Southern Michigan: May-June
Osprey fledge in late summer and migrate south in the fall. The adults usually return to the same nesting sight ever year.
We recommend that volunteers visit a nest 3 times throughout the summer months and want them to report on nests that are successful in raising chicks. Make sure to count the number of chicks that fledge the nest, if possible. It is important to visit a nest more than once to determine if it is actively being used or not. If you have visited a nest site a minimum of 2 times and several weeks apart during the summer time frame and you have seen no activity, you can assume the nest is no longer active.
Most monitoring sessions should be able to be completed in 30 minutes or less and the observations should be able to be made with a pair of binoculars, though a spotting scope is helpful for monitoring cell tower nests.
How to Become a Volunteer
Contact MNFI (mnfi@msu.edu) if you would like to monitor a nest in your area and provide the county you wish to observe.
Osprey Adopt-A-Nest Partners
