Feral Eggs and Youngsters

[Snowbird]

For those with an interest in feral pigeons (though some information may apply elsewhere)

* Nest building occurs 5–7days after the first mating.
* Mating occurs 5—7 times per day.
* Some repetitive nest sites are built on the old site. Nests have be known to be 20 cm high, 50 cm wide and 2 kilograms (Kansas). It contained several crushed eggs and two mummified chicks—geeeez.
* The favored nesting spots are not cliffs, though they are used in the wild populations remaining in the harsh west coast of England and Scotland. These nests are vulnerable to Gyr Falcons, Peregrine Falcons, and a deadly gull called the Skua, not to mention hellish weather. The ancestral breeding grounds of choice are the caves on the same cliffs—places of near darkness. (So if you put homer cocks in a new nest loft, the strong bird will tend to take and defend the highest darkest “cave”).
* Clutches are 2 egg—91.9%, 1 egg—7.7%, 3 egg--.05%, one case of 4 eggs has been documented in a hen/cock couple.
* The choice of 2 eggs is due to the limitation of crop milk which is typically insufficient for more than two chicks.
* Winter and summer eggs have a different chemistry of yolk and albumen and overall size.
* You may have seen your birds pseudo-incubate. It’s when they are sitting on a phantom egg—they open the breast feathers to expose the “hot spot” flesh and they use their beaks to move an egg that isn’t there.
* If the hen parent dies the nest is abandoned. If the cock dies the hen stays on the nest unless this happens early in the term.
* The egg loses about 22% of weight during incubation in the form of respiratory water loss.
* Maternal Immunoglobin G and tansferrins in the egg yoke and albumen take care of the immune response before the chick develops an immuno system. This is also in “pigeons milk” and the adult saliva.
* The process of incubation stimulates the release of prolactin which stimulates the production of “pigeons milk”.
* Hatching losses in ferals is 7—25% averaging about 10%. The greatest losses are in the first 5 days.
* Male eggs are more often laid first and females second (a majority of clutches have a male egg and female egg).
* The first egg has approximately one day’s head start on the second egg, even though the eggs are about 44 hours apart on average.
* Brood reduction strategy via hatching asynchrony is valuable when food is scarce—this assures one chick will survive. Other species may not incubate until all eggs are laid. (If you breed pigeons you may take the first egg to a cool place until the second egg is laid). In ferals on average, 70% of the first eggs fledge and only 57% of the second eggs fledge.
* If the second egg hatches 2 days after the first, 60% of the second chicks die. Later than that and they all die.
* Other species have the first egg be the smaller gender (could be male or female) because the smaller youngster has a smaller price in terms of food energy required, but pigeons give the larger male the first egg.
* The first egg has more protein in winter.
* Birds paired quickly and arbitrarily have a higher degree of one egg clutches and infertile eggs. The courtship rituals key the biological preparations and if they are not well done, the mating is jeopardized.
* Hatching temperature for chicks is between 31.5 and 32.8°C; weight is about 14 grams.
* The chicks blood has a high hemoglobin which allows for greater warmth = greater heat capacity.
* By day 8 the youngster is 37°C; adult temperature of 41.4°C is reached by day 17—18.
* Peas are not introduced until day 7, after which time they become very important.
* Youngsters usually walk between the 12—17th day.
* The last feathers to develop are those on the anterior part of the head—perhaps this is due to the fact that the chick sticks the mandibles into the parent’s mouth to feed.
* The youngster is normally independent between 30—45 days.
* The period between 6—10 weeks is the time of most susceptibility to disease.