Case of Cephalic Presentation of Foetus in a Harbour Porpoise Phocoena Phocoena (Cetacea, Phocoenidae), with Notes on Other Aquatic Mammals
A stranded harbour porpoise pregnant with a near-term foetus in cephalic (head) presentation was found. It is the first time when cephalic presentation, now recorded in three odontocete families, is reported for phocoenids. It proved to occur rarely, yet to be more widespread for aquatic mammals than could be expected.
The first assessment of abundance of a local population of bottlenose dolphins in the Black Sea (near the Sudak coast) in 2011–2012 has been conducted: the results of a mark-recapture study of photo identified animals were complemented by a vessel line transect survey. The overall abundance of a population was estimated at between 621 ± 198 and 715 ± 267 animals (Chapman and Petersen estimates), and the majority of members of the population were recorded in the surveyed area. The summer range covered the area of a few hundred square kilometers, similar to migrating coastal stocks in other world regions. The greatest density of distribution was observed in August in sea 45–60 m deep; in addition, frequent approaches to the coastline are usual for dolphins of this stock. These trends in distribution may be partly explained by distribution of prey. Interaction with sprat trawling fisheries can be a factor shaping the local population structure. Coastal waters of Sudak and adjoining sea areas are an important habitat for bottlenose dolphins in the northern Black Sea, significant for their conservation.
We report 7 new prey fishes in diet of the Black Sea bottlenose dolphins Tursiops truncatus (Montagu, 1821) and the first records of 9 prey items from their stomach contents: herring (Alosa sp.), sand smelt (Atherina sp.), horse mackerel (Trachurus mediterraneus), picarel (Spicara flexuosa), Mediterranean sand eel (Gymnammodytes cicerellus), Atlantic stargazer (Uranoscopus scaber), garfish (Belone belone), gobies (Gobiidae indet.) and blennies (Blenniidae indet.). Th e Atlantic stargazer was recorded as a prey species for the common bottlenose dolphin for the first time. Th e horse mackerel and the picarel, formerly recorded in the diet of Mediterranean bottlenose dolphins, now were frequently found in the examined Black Sea dolphins. Th e list of prey fishes for Black Sea bottlenose dolphins now includes 23 items, with many small pelagic and demersal fishes, and it is similar to that of Mediterranean dolphins. Whiting (Merlangius merlangus) is still an important prey species, as 50-70 years ago, whereas turbot (Psetta maeotica), not recorded by us, could lose its importance due to population decline. As before, red mullet (Mullus barbatus) is recorded in winter feeding. Feeding on mullets (Mugilidae) is not a universal trait, and it is possibly restricted to local geographical areas.
We analysed the sex and age composition of a large colony of Nyctalus noctula (605 specimens), wintering in Kyiv, Ukraine. Age was identified in 113 individuals using the method of counting growth layer groups in dentine. Males contained ca. 70 % both in the colony and in the sample of animals with the estimated ages. Males and females of all ages were in good body condition. There were bats from 0+ to 7+ years old in the sample. In males, 0+ age class was represented by 38 %; 1+ class, by 20 % of individuals. In females, 0+ and 1+ year old individuals were found in similar numbers: 29 % and 32 % correspondingly. The observed sex ratio and proportions of males and females across age classes cannot be explained only by demography. The data are interpreted in terms of migratory behaviour and mating strategy of the species: the unusual female age structure is possibly due to age-specific preferences in wintering habitat selection and search for potential mating partners.
Isolated odontocete teeth were found in two Miocene sites in the Dniester River valley. Cetaceans from the both sites possibly represent unknown taxa. One of them is a stem physeteroid, the most similar to Scaldicetus caretti and Early Miocene taxa; another one can be a stem physeteroid or a large stem delphinoid.
The first assessment of cetacean density and abundance by linear transect survey was conducted in 2016 and 2017 in the shallowest coastal area of the Ukrainian sector of the north-western Black Sea, in the Dzharylgach Gulf and the northern Karkinit Gulf, total area up to 259 km2. Three cetacean species were found present in the area in summer, and the harbour porpoise was the most abundant species with the abundance of at least a few hundred animals (estimated as 175 individuals in the Dzharylgach Gulf), whereas the common dolphins (59) and bottlenose dolphins (31) were present in lesser numbers. Common and bottlenose dolphins showed the clearest patterns of habitat preferences, being restricted respectively to the Dzharylgach and the northern Karkinit Gulf; an unusual trait is the preference of the shallowest habitat by common dolphins. Recorded density of harbour porpoises in the Dzharylgach Gulf is among the highest in the whole Black Sea. Thus, the studied area may be an important summer habitat for cetaceans.