As the ospreys continue to build their nest, we’ll be eagerly awaiting the arrival of eggs. Once hatched, osprey chicks must survive several challenges, including attacks by predators, staying in the nest during strong winds and more.
Q: How do you know if a bird is a male or female?
Ospreys are dark brown on top and white below with white heads, fierce beaks and dramatic black stripes extending from their eyes (like a particularly aggressive cat-eye liner). Females are larger than the males and have a pronounced dark feather “necklace,” while males have lighter markings.
Q: When do the eggs hatch?
The female incubates the eggs for about 40 days. When the chicks hatch, she sits on them for 10 more days. Brooding keeps the chicks warm until they can regulate their own body temperatures. The mother bird doesn’t lay on the chicks as firmly as she would on the eggs, and the chicks adjust themselves underneath her. The chicks likely will hatch a few days apart rather than all at once.
Q: What do ospreys eat?
The family diet is 99% fish. When the chicks are 10 days old, they are already mobile and eat between 1 and 3 pounds of food per day!
Q: How much do the chicks need to eat to survive?
When chicks are small, it doesn’t take much to fill their stomachs, so they need to be fed several times a day. As they grow and their stomach capacity increases, they eat larger meals until they only need one large meal per day.
Female and male osprey on the Osprey Cam nest. Photo by Richard Bachrach
Q: Who does the feeding and fishing?
During the brooding phase, the male will do most of the hunting. When the male delivers the fish, the female eats a few pieces of the fish that are harder to digest. She gives the chicks the softer parts because their digestive systems cannot digest tough skin, scales or larger bones yet.
Q: Do the chicks go to the bathroom in the nest?
Yes. When the female gets ready to feed the chicks, a chick clears its cloaca (the combined opening for the bird’s intestinal, reproductive and urinary tracts) and eliminates its waste — in projectile fashion. This makes room for the next meal and also helps keep the nest clean.
Sources:
- The Raptor Center at the College of Veterinary Medicine at the University of Minnesota
- Three Rivers Park District
- Cornell Lab, All About Birds
- Rachel Carson Council
Special thanks to the Garwick Family Memorial Fund and Jo Frerichs for generously sponsoring the costs of the live Osprey Cam.
Cover photo of osprey building the nest by Richard Bachrach