June 28, 2010 - One Fish, Two Fish, Red Fish, Blue Fish
Osprey are amazing fishers, with 99% of their diet being live fish. Diving from 10-40 meters above the water, osprey extend their legs forward in front of their head, plunging feet first into the water. When flying with a fish in its talons, an osprey will align the fish so that the head is facing forward...watching the birds accomplish this while on the wing is quite remarkable.
Osprey are picky eaters, tending to focus on a few species regardless of how many fish are in the water. When learning to hunt without the aid of their parents, osprey chicks focus on one species of fish until they master the art of catching it. We've noted in previous years that our osprey have mastered the art of backyard koi pond fishing....and a web cam watcher from afar has confirmed that a koi was fed to the chicks this last weekend. For all those with koi ponds in the Inglewood area, this is your osprey advisory!
The young get their first taste of fish from their parents. Usually the male brings back a fish or portion of a fish and presents it to the female. She then rips off parts of flesh and feeds it to the chicks in a unique way. Instead of feeding it to a specific chick (as robins do) the osprey feeds to a window in space. The chick that gets there first gets the food. This ensures that in lean years, when fish are not abundant, the most dominant chick survives. Our female's feeding style is interesting....her window is quite far from her chicks, so it will be interesting to note how this technique affects them over the next few weeks.
Lisa McDonald and Tanya Hope
June 22, 2010 - News from the Nest!
Wonderful news, we have 2 hatchlings on the nest. I’d received several e-mails from webcam watchers worrying whether the eggs were viable after being covered by the black plastic bag in the first days of gestation. I’m sure that we’re all quite relieved knowing that nature has prevailed. Mum and dad have been trading places on the nest, and seem to be coping expertly. Ospreys are fully fledged in about 50 days-it is a joy to see young birds grow and thrive with such a high degree of parental care.
I’m not sure if you’ve been following the saga of Lady, the 25 year old osprey in Scotland. The story is very touching and a visit to the website might be in order if you’re interested in learning more.
Several of you have been speculating on the black object in the nest next to the hatchlings. Over the years the ospreys have selected police hazard tape, a toque, a mitten and the infamous black plastic bag to place in the nest. The jury is still out, but the black object is being interpreted by some here as a black under-wire bra.
Lisa McDonald is the Calgary Zoo's
Visitor Education Specialist
June 16, 2010 - Anticipation
Today there are still 3 unhatched eggs in the nest. We continue to wait for the moments when the osprey takes a brief break from incubating so we can see into the nest bowl. Hopefully soon we'll have a hatchling...that's when the activity at the nest will increase markedly.
Lisa McDonald is the Calgary Zoo's
Visitor Education Specialist
June 8, 2010 - Three's A Crowd
In an interesting development this week, a third osprey has appeared at the nest. Mum and dad continue to alternate brooding the eggs despite the interest of this third party. We have banded all of the nestlings at this site for the last 15 years and the new osprey is unbanded, so we know that this bird is not one of the nestlings from a previous year. Once the eggs begin to hatch it is unlikely that appearances by this individual will be tolerated by mum and dad as graciously as they have been this week.
We are expecting the first egg to hatch between Sunday the 13th and Tuesday the 15th, so keep watching closely.
Lisa McDonald is the Calgary Zoo's
Visitor Education Specialist.
June 2, 2010
Osprey young are altricial-they hatch helpless and require a high degree of parental care. Osprey females begin to incubate from the moment the first egg is laid. The first chick to break out of the egg is then 2-3 days older than the next to hatch. As a result, a floppy bodied, damp hatchling will be in the nest next to a robust chick that clamours for food when mom or dad returns to the nest with a tasty tidbit. Some bird species don't begin to incubate until the last egg is laid, so all their offspring hatch at the same time.
In terms of egg development, the first part of the embryo that forms is a layer of cells that will become the chick’s head and backbone. The heart and limbs develop next. Talons form just before hatching.
Lisa McDonald is the Calgary Zoo's
Visitor Education Specialist.