Publisher Summary Birds exhibit a wide spectrum of parental care patterns ranging from brood parasitism, in which no parental behavior is displayed, to full-time attentiveness to the eggs and young by one or both parents. This chapter reviews the neural and hormonal mechanisms that regulate parental care expression in galliform and columbiform species. It attempts to relate the evidence to that obtained in other avian species that have received less experimental attention. For purposes of this discussion, parental behavior is defined as those activities directed toward care of eggs or young. However, it is important to emphasize that these behaviors arise from antecedent events. At the risk of minimizing the importance of physiological and stimulus continuity in promoting transitions from one form of parental activity to another during the breeding cycle, the neural and hormonal regulation of parental activities exhibited prior to hatching (that is, incubation behavior) are discussed separately from those occurring after hatching (brooding and feeding the young). The chapter also discusses the physiological determinants of nest defense behavior that is displayed both before and after hatching in many species.

Neural and Hormonal Control of Parental Behavior in Birds

We wish to dedicate this paper to the memory of Professor A. J. Marshall whose untimely death occurred while it was in press. Professor Marshall was formerly the head of the Department of Zoology, St. Bartholomew's Hospital Medical College, London, and subsequently held the Foundation Chair of Zoology and Comparative Physiology, Monash University, Australia. Probably the most valuable of his many contributions to the field of avian physiology was his ability to relate laboratory experimentation to the natural environment. Much of the thought contained in the present paper has been stimulated by his approach and pioneer studies.

Photoperiodic and physiological adaptations regulating avian breeding cycles and their ecological significance

In previous communications, the motility of the chick embryo up to 17 days of incubation had been characterized as spontaneous rhythmical uncoordinated random motility. On the other hand, the opening of the shell and hatching are accomplished by a sequence of vigorous back thrusts of the head and beak against the shell. The head movments are part of a coordinated action pattern which includes wriggling movements of the body which have a rotatory component, resulting in the rotation of the body along its axis; and the bracing of the shoulder and tarsal joints against the shell.



We have found that similar coordinated movements including a rotatory component are instrumental in several other action patterns which are preparatory to hatching. They include: the lifting of the head out of the yolk sac; the tucking of the head under the right wing; the assumption of the typical hatching position; and pipping. Another preparatory step, namely the penetration of the membrane separating the embryo from the air space does not require coordinated movements. All these movements were observed through windows in the shell; they are described in detail.



Coordinated movements appear to originate de novo around day 17. They do not seem to be related to the random movements which are characteristic of earlier embryos. The latter continue until the onset of hatching, but they are suspended temporarily while the coordinated movements are performed during tucking, pipping and hatching.

Prehatching motility and hatching behavior in the chick.

The multiple nature of the animal protein factor.

https://www.jstor.org/stable/info/1365062

The Incubation Patch of Passerine Birds

ConclusionsIt has been found that single fowl pituitaries implanted over the crop glands of 8- to 10-weeks-old pigeons (age computed from time of conception) will, in many instances, cause a prolactin-like reaction. It is assumed that this reaction is caused by prolactin in the pituitaries of the donating fowls.Pituitaries from broody hens cause a greater reaction of the pigeon crop gland than the pituitaries of laying hens. Pituitaries from males cause a reaction about equal to, or slightly less, than the pituitaries from laying hens.It was noted in a few cases that the pituitaries of hens just becoming broody gave a greater reaction than those of hens nearly over their broody period. More data are being gathered on this point.

Studies of Prolactin in the Fowl Pituitary. I. Broody Hens Compared With Laying Hens and Males

The growth of chick embryos of heavy and light breeds and the reciprocal crosses between them is described. The embryos of the heavier breed and the hybrids were found to be somewhat heavier than the embryos of the lighter breed from the tenth day of incubation to hatching time. In eggs of the same weight from the two breeds the size difference tends to disappear toward hatching time, probably due to the equivalence of the strictly limited food supply. It is pointed out that the size difference is more probably due to difference in the proportion of cells dividing at a given time than to a difference in duration of mitoses.



The mortality of the hybrid embryos was intermediate between that characteristic of the parent breeds, while the percentage of monsters in the hybrids was less than that for either parent breed. There is thus some indication of heterosis.

The effects of breed on the growth of the chick embryo

The Effect of Certain Groups of Environmental Factors upon the Expression of Broodiness

Under optimum conditions, young healthy individuals of each livestock species may convert about one-third of the digestible protein in its feed into tissue protein in its body. Of this tissue protein, we use about half as food.

https://science.sciencemag.org/content/sci/157/3791/890.full.pdf

T. C. Byerly

Papers

Studies of Prolactin in the Fowl Pituitary. I. Broody Hens Compared With Laying Hens and Males

The effects of breed on the growth of the chick embryo

The Effect of Certain Groups of Environmental Factors upon the Expression of Broodiness

Efficiency of feed conversion.

The Influence of Gravity and Air-Hunger on Hatchability