THE BIRDS OF BLYTHSWOOD AND SOME NOTES ON BIRDS OF THE DISTRICT

Wintle, C. C. &; Taylor, P. B. 1993. Sequential polyandry, behaviour and moult in captive Striped Crakes Aenigmatolimnas marginalis. Ostrich 64:115-122.

Captive Striped Crakes showed sequential polyandry, the female laying for a second male when the clutch of her first mate was about to hatch. Where aviary space permitted each male set up a breeding territory and each female defended a larger area encompassing the territories of one or two males. Non-territorial subordinate males and females did not breed. The female initiated breeding by attracting the male and soliciting copulation, and the male incubated the eggs and cared for the young. Incubation took 17–18 days, the chicks left the nest at 4–5 days of age and were fully grown and capable of flight at 46–53 days. Breeding occurred from September to March and males normally reared two broods per season. Territoriality was evident only during the breeding season. Juvenile plumage was a duller version of the sexually dimorphic adult plumage; post-juvenile moult bean at 13–15 weeks and was complete at 21 weeks. Remex moult was simultaneous and a complete moult regular1 occurred twice a year in adults, in December and April (males) and September and March/April (females).     

ON THE BIRDS OF MOROCCO

Fifteen months were spent in Morocco. A few ecological aspects of the country are described, together with their influence on the dispersal of birds in winter. Some winter visitors are listed and discussed, several species were much commoner in the winter of 1962/63 than in 1963/64, in some cases presumably as a result of the cold weather in Europe, although in others not obviously so. Cold-weather movements of gulls, Lapwings and Cranes were observed. Individuals of species that are normally trans-Saharan migrants winter in Morocco in small numbers. Spring migration in southeast Morocco is excluded from discussion, but autumn migration in western Morocco is summarized and compared with existing data. The systematic list is devoted largely to winter visitors and passage migrants, but resident species are listed when new localities, breeding data or field notes warrant their inclusion. Six species not hitherto recorded in Morocco, were seen.     

THE INCUBATION PATCH OF BIRDS

1. The incubation patch of birds forms in the areas of the ventrum devoid of contour feathers (apteria) by processes involving defeathering of down, dermal and subdermal hypervascularization, oedema, and hyperplasia of the epidermis and dermal connective tissue. Its formation facilitates the transfer of heat to the eggs and hatched young. 2. In general, the sex that incubates develops a patch; this may be the female, both sexes, or the male, and the species within any one order tend to exhibit a common pattern. In some orders (e.g. Pelecaniformes) no patch develops. 3. The incubation patch begins to form before egg laying in passerine birds and during egg laying in Galliformes. Most of the patch responses in passerines are completed earlier in the reproductive cycle (late egg laying to middle incubation) than in Galliformes (middle incubation to early brooding). 4. In the passerines studied, in which usually only the female develops a patch, oestrogen and prolactin synergize to cause patch development; oestrogen given alone is effective because it synergizes with endogenous prolactin in intact birds. The role of progesterone is unclear, but it seems to mimic the effects of prolactin and also plays a role in the increase in skin sensitivity characteristic of patch development in the canary. 5. In the one galliform studied (California quail), in which both sexes develop a patch, either oestrogen or androgen synergizes with prolactin; oestrogen alone is ineffective in non-breeding quail because of insufficient endogenous prolactin levels. Prolactin alone causes epidermal hyperplasia and vascularization, and progesterone seems mainly to be involved in defeathering. In the starling also both sexes develop a patch, but testosterone plus prolactin is not effective as it is in the quail. 6. In the phalaropes, birds in which only the male develops a patch, androgen and prolactin are the effective synergists in patch development. Thus, there is a correlation between the sex which develops a patch in the wild and the steroid (oestrogen or androgen) which synergizes with prolactin. 7. In the brown-headed cowbird, a parasitic species which neither develops a patch nor incubates, there are no responses to exogenous hormones. The absence of patch development in one sex or in both can be due either to an absence of appropriate hormone levels or to a lack of sensitivity of the skin to hormones. 8. More study is needed of the transfer of heat from the patch area to the eggs or young, including the relationships between patch structure, surface area, surface temperature, type of nest, and the number and size of eggs. 9. Patch formation is affected by and influences behaviour. 10. More research is needed in regard to (I) the natural development and endocrine control of the incubation patch in various orders of birds: (2) the effects of patch formation on behaviour, and vice versa; (3) the mode of action of the hormones in patch formation, that is, whether it is direct or indirect, e.g. through the release of another hormone; (4) the specificity of the ventral skin to hormone administration; (5) the effects of stimulation of the patch by eggs in the nest on prolactin and gonado-trophin secretion; (6) the possible role of other, as yet untested, hormones on patch development; (7) the levels of endogenous hormones in relation to natural patch formation; and (8) possible correlations between the structure of the patch, the chronology of its formation, the clutch size and the condition of the young when hatched in various species.     

THE SENSE ORGANS OF BIRDS

The eyes and ears of birds are compared with those of man so far as the existing state of knowledge allows, and an attempt is made to correlate resemblances and differences with the evolutionary history and the functional requirements of the present day. It is shown that the characteristic shape of the central fovea of the bird's retina cannot be accounted for by supposing that it increases acuity; it is more likely a device for emphasizing angular movements. A brief account of Menner's theory of the pecten is given.
In default of any satisfactory physiological data, an attempt is made to assess the indirect evidence relating to the frequency range and discriminative power of a bird's ear. The conditions for the unambiguous determination of the direction of a sound source are discussed and it is suggested that the asymmetry of the ears of owls is correlated with an enhanced directional sensitivity which, in turn, is related to the dependence of owls on hearing rather than sight in their hunting.
Reference is made to the senses of smell and touch in birds. And there is a brief discussion of the problems of "time" and "direction" senses.     

THE BIRDS OF LANGEBAAN LAGOON

Data are presented on breeding success of Red Bishops (Euplectes orix) collected over four breeding seasons at a colony in the Addo Elephant National Park, Eastern Cape, South Africa. Overall hatching and fledging success were 53.8% and 26.0% of all eggs laid, respectively, and the overall mean number of fledglings per breeding attempt was 0.77. Hatching and fledging success varied significantly among seasons, with both clutch and brood losses due to predation being the main reason for the observed differences. Hatching success also differed significantly among clutch sizes, being highest for four-egg clutches (63.2%), intermediate for three-egg clutches (55.5%) and lowest for two-egg clutches and five-egg clutches (33.2% and 34.3%, respectively). However, fledging success was not significantly different among clutch sizes. The mean number of fledglings per breeding attempt was 0.44 for two-egg clutches, 0.80 for three-egg clutches, 1.10 for four-egg clutches, and 0.57 for five-egg clutches. The height of accepted nests (i.e.nests in which at least one egg was laid) was significantly lower than the height of nests not accepted. In addition, accepted nests in which eggs hatched and young fledged were significantly lower than accepted nests in which no eggs hatched and no young fledged. These overall effects of nest height on nest acceptance and hatching and fledging success were, however, due only to nests built above water, since no such effects were found when nests built above ground (i.e.on dry land) were analysed separately. I detected no effect of nest coverage on the probability of a nest being accepted, nor was there any effect of nest coverage on hatching or fledging success. Nests above water were significantly more likely to be accepted than nests above ground; however, hatching and fledging success of nests that were accepted did not differ significantly between nests built above water and those built above ground.