Pittsburg

An early visitor...

The mess in the Zurich nest

It's often a total mess in a peregrine nest. Leftover bodyparts of prey, birddroppings, flies just love it all. The Zurich nest is a fair example. many people wonder if this mess isn't affecting the eyases.

Peregrines , birds in general, have a very different immuunsystem than we have. When the eyases are born they've just consumed what's left of the yoke and amnionfluid. That's the first time they really consume it. In the egg, nutrients are extracted from the yolk and transported by the blood. In the leftover yoke are a few antibodies the mother put in the egg in order for the chicks to stay alive in the first days. Because the eyases are born with an incomplete immuunsystem.
Immunity starts its developement after hatching. Most important are the first 6 weeks of their life. Peregrine chicks are not born with a kind of genetic databank of information B-cells can use to produce antibodies. As we have. White bloodcells who produce antibodies are B-lymfocytes. B stands for Bursa. This Bursa is a very unique organ only found in birds. Its situated in the cloaca.

It's a kind of "university" where just created B-lymfocytes migrate to, to learn to create antibodies. In order to do so they have to be brought into contact there with a diversity of pathogens like bacteria, virusses, parasites etc. Besides the pathogens in the food they eat they do this by cloacal drinking. The little eyases are able to suck up nest material with their cloaca to bring to the Bursa where the B-lymfocytes are trained to make antibodies to these specific pathogens. Once been into contact with a pathogen, the B-cells know for the rest of the peregrines live how to make antibodies. Pathogens which haven't been brought into contact with the B-cells in these first 6 weeks will be very sickening in the rest of the peregrines life. Maybe even deadly, like the West Nile virus and the Avian Flu.

So it is very important for the peregrine chicks to get into contact with as many pathogens as possible, because after 6 weeks, it's over. The university closes and that's it. A messy nest provides in a lot of pathogens.

But the mess creates a very nice enviroment for all kinds of pathogens as well, like bacteria, flees, lice, protozoa and flies. And these can be and are very dangerous for little eyases. All of them have lice and flees, which can be deadly as soon as the eyases don't get enough food.

When the eyases get older parents leave prey leftover in the nestbox, and when the juvies leave the mess is complet. Rain, sun, autumn storms, winter cold, it cleans a nest, but not enough. Especially not the ones that have a roof. It is recommended to clean those every fall.

Egg production

Most birds have only one ovary and one oviduct. In early stages of embryonic development, each female bird has two ovaries; only the left one develops into a functional organ. In some birds, such as peregrine falcons, the right ovary and oviduct usually develop. A mature ovary looks like a cluster of grapes. and may contain up to 4,000 small ova which can develop into mature ova.
With fertilization, the ovum or egg becomes a developing embryo
The embryo passes through the oviduct typically takes about 24 hours (for passerines & most other birds)
The demand for calcium to make the egg shell is very high, and so the circulating levels of blood calcium in birds are greatly elevated compared to mammals, typically twice as much.

The ovary enlarges greatly during the breeding season. Active ovaries resemble bunches of tiny grapes -- the developing follicles. The oviduct opens medially to it in a funnel-shaped ostium. Ovulation results in the release of an egg from a mature follicle on the surface of the ovary. The egg, with extensive food reserves in the form of concentric layers of yolk, is picked up by the ostium an ciliary currents carry it into the magnum region. Over about three hours the egg receives a coating of albumen. The egg then passes into the isthmus, where the shell membranes are deposited. This takes about one hour. The egg them moves to the uterus, or shell gland, where the calcareous shell is added and, in some birds, pigment is added in characteristic patterns. The egg then passes into the vagina and cloaca for laying.