Аннотация:A. Portman (1935, 1962), studying the development of birds and mammals, tried to create a system of the types of ontogeny based on morphological and behavioral complexity of the organization of adults. Portman thought that the main line of evolution of birds was an increase in the role of parents in raising chicks, and the altricial type of ontogeny came under regulatory control progressively developing an instinct of caring for offspring. Convincing picture of the development of parental care on the scale superprecocial – altricial drawn by D.N. Hoffman (1955, 1962). Hoffman believed that the evolutionary process of the origin of altricial birds aimed to reducing physiological stress of the female during reproductive period. Indeed, the energy content of eggs (q) changes in altricial Passerines with changing their mass (m) as the q = 1.124 m0,9438 kcal/egg, while in semiprecocial and precocial birds like q = 1.910 m0.9574 kcal/egg (Stark, Ricklefs, 1998; Kendeigh et al., 2012), which shows a greater energy price for eggs in precocial ones. However, the dependence of the energy value of the eggs on species ecology is great: a greater energy contained in different precocial waterfowl and waders eggs, altricial and semialtricial penguins and Procellariiformes, semiprecocial guillemots and gulls (Nice, 1962; Dolnik, 1995). Energy consumption for the synthesis of 1 egg is well expressed in terms of day costs for the metabolism, in BMR (basal metabolic rate). So, the cost of altricial cuckoo egg is 0.35 BMR, and egg of Procellariiformes, costs 2,44 BMR. Of course, it is necessary to assess the number of eggs laid by a female in a season. There are usually 1-2 eggs in Procellariiformes (2.4-4.9 BMR), in the common cuckoo – about 10 eggs (3.5 BMR). The cost of feeding and heating the brood in precocial birds is less than feeding and heating nestlings and flegings in altricial birds. When feeding young main energy costs of parents are associated with the distance from the point of prey capture to the nest. The energy cost of transporting food to the young determined by the price of pedal (1.6 BMR) or flight locomotion (16 BMR - Gavrilov, 2011). High values of energy expenditure (DEE) are established in the colonial sea divers (mainly altricial, semialtricial and semiprecocial) as about 4 BMR (Dolnik, 1995). Large energy consumption in precocial females for laying eggs are compensated by lower energy consumption when driving the brood, while birds with altricial and semialtricial types of ontogeny have lower cost of eggs that is balanced by high energy consumption in the feeding of nestlings and fledglings.
The selection for the birds that began to hunt in the air, nest in trees, rocks, holes, build complex nests, is possible only with a simultaneously increase of immaturity at birth. The immaturity at birth increases the training period of the perception and the training of coordination the sensory information and motor activity. In altricial birds the critical imprinting periods for acoustic and visual communications are significant stretched. Training of perception and memorization of complex signals are only possible after establishing of the relative endothermy, the setting of effective termoregulation – the moment when the chick is already able to keep its body temperature above 37 °C in the temperature range of adult thermoneutral zone. The critical period of imprinting of complex acoustic and visual signals coincides with the time of setting effective thermoregulation. The development of thermoregulation in precocial birds occurs inside the egg very slowly until pipping, then the velocity of the capability for thermoregulation grows fast and after hatching the effective thermoregulation is achived in one or several days. In altricial birds the termoregulation, as well as hearing and vision, develope outside the egg under the influence of the external environment and species specific signals. The critical periods of imprinting in precocial birds is short, in altricial it is long. The long critical period is necessary, for example, to learn to catch prey in air, to get capability to build a nest.
Palaeognathae do not fly and have precocial type of ontogenesis, most Neoaves are altricial, semialtricial or semiprecocial. Among Galloanseres Anseriformes are precocial (waterfoul), Galliformes have a trend to be less precocial. The precocial type of onthogeny of waders is apparently secondary, many waders are semiprecocial.