Osprey Say Green Is In

The osprey nest cam at the Great Bay Discovery Center gives a perfect view of the frozen saltmarsh at this time of year, but with only 3 months until the osprey pair returns to their nest, staff often use this window of time to venture out to clean up debris that would otherwise be hidden by tall green cordgrass.

Material pollution exists worldwide and is a well-known issue that plagues many ecosystems, the most well-known being our oceans. Oceans make up 70% of Earth, and are a crucial part of the environment because they provide habitat for so many species. Pollution in marine environments, whether floating in the water column or washed up on beaches, can be detrimental to all species that encounter it. 

Osprey are a species that will often add man-made material to their nest. A study on Osprey (Pandion haliaetus) in the Cabo Verde Archipelago off the coast of Western Africa showed the use and abundance of marine debris selected for building material in nests. Out of 36 nests observed, 92% contained anthropogenic marine debris, proving that our material pollution expands much farther than we can see. Materials found include processed wood, synthetic foam, rubber, clothing, and metal. Plastic was the most frequent material found in nests, and rope and netting were the most abundant objects. Other objects included bottles, tape, pipes, and hoses, showing the diversity of osprey selection. Interestingly, green was the most common color of materials collected, possibly due to the mistaken identity of objects for branches or vegetation, or the low availability of suitable natural nest-building material in the study area, which goes to show the importance of diverse vegetation along coasts. The second common color found was white, possibly sought after to camouflage eggs and young chicks. 

More concerning, within this study, researchers found two live females whose legs were entangled with rope and netting. Any entanglement is potentially life-threatening as it could interfere with flying, hunting, and eating. The presence of anthropogenic material in nests can not only cause entanglements, but the risk of ingestion and physical injury to eggs, chicks, and adults is very real.

 The use of colored material in building nests could be harmful not only because of entanglement risk but could also lead to predator detection due to differences that birds and predators have in their ability to see color. Certain organic materials provide pathogen and parasite resistance, and ventilation and temperature regulation of the nest. Unknowingly using a different material, such as one with insulating properties, could have adverse effects on hatch rates, chick growth, and survival. Other interesting results of the study conclude that nests closer to water as well as larger nests, contained more anthropogenic debris than nests located more inland, showing the additional impacts of water born pollution.

 As osprey nests are reused every year, their construction and stability parameters for longevity are important. Expanding our knowledge on the reach that our pollution and choices have is critical for the prevention and undoing of damage created. The life threatening consequences that our trash has on wildlife should push us all to be as “green” as possible and make the choices that foster our roles as stewards and advocates of the Earth.

Want to read the article?

Rodríguez, B., López-Suárez, P., Varo-Cruz, N., Dack, E., Rendall, A., Siverio, F., … & Rodríguez, A. (2023). Use of marine debris as nest material by ospreys. Marine Pollution Bulletin194, 115422.