PECULIARITIES OF EMBRYONAL DEVELOPMENT OF THE COASTAL SWALL (RIPARIA RIPARIA L.) IN THE KAMA PRE-URAL (NORTH OF AREAL)
The article deals with the features of embryonic development of the coastal swallow nesting in the North of the area within the Kama Urals. One of the important adaptations in the embryogenesis of coastal swallows is the incubation of the clutch from the first laid egg, which prevents the elimination of embryos. During the egg-laying period, the incubation density gradually increases. In parallel to the egg laying in females of coastal swallows, the formation of a sedentary spot from the first to the third stage occurs, which increases the heat transfer from the female body to the demolished eggs. In clutches there is a different age of embryos. Embryos develop heterochronically. Embryos from the first eggs develop at a slow pace, from the latter-at the maximum rate. In the period of incubation itself, there is a further increase in the incubation density, the nasednoe spot reaches the 5th stage of development, the intraocular temperature increases. Until the third day of incubation (since the last egg was laid), the difference in age between embryos from the first and last eggs is 9-11 stages, then from the 4th to the 12th day of incubation the difference between the extreme variants does not exceed 3-5 stages. The consequence of the decrease in the value of different ages in the clutches of coastal swallows by the end of embryonic development is the friendly hatching of Chicks. The difference in the rate of embryonic development of embryos from the first and last eggs of the clutch is somewhat smoothed at the end of embryogenesis due to the manifestation of compensatory growth and creates conditions for more friendly hatching of Chicks, their better survival in postnatal ontogenesis.