Large herbivores in restricted ecosystems: assessment of water sources value by high-usage movement pathways at Byriuchyi Island spit

• Main Author: Mariia Polzyk
• Format: Article
• Language: English
• Published: National Academy of Sciences of Ukraine. National Museum of Natural History 2020-12-01
• Series: Theriologia Ukrainica
• Subjects: large herbivores; pathways; byriuchyi island spit; habitat selection
• Online Access: http://terioshkola.org.ua/library/pts20/TU2006-polzyk.htm

An animal population permanently living in a certain area not only adapts to environmental conditions, but changes the environment as a result of their activities. The constant movement of animals between valuable resources in a certain territory forms a system of permanent trails. They are valuable source of information for solving problems of directed formation of ecosystems, organisation of protection and rational use of the territory. The territory of our study — Byriuchyi Island — is an alluvial type of sand and shell rock spit. It is covered with a variety of wetlands, meadows, and steppe vegetation. There are no natural sources of fresh water. Since the 1950s, several species of large herbivores have lived here: red deer, fallow deer, onagers, and feral horses. To provide animals with fresh water, artificial ponds called “kopanki” were created in the 1970s. In order to determine the intensity of use of drinking water on the Biryuchy Island spit, we assessed them based on the analysis of the system of permanent trails. Materials used in the work consist of data collected in 2014–2018 during field research and satellite images of the area. During the study period, the total number of ungulates ranged between 2700 to 3400 individuals. To assess the intensity of water use, the number and direction of permanent paths were determined, the distance to other water and fodder sources, shelter, microrelief and climatic features, anthropogenic factors were estimated. Data were collected for 31 artificial water sources. It has been found that permanent trails can extend from the source in up to 25 directions. However, more often they are concentrated in the northern and north-eastern directions. This is due to the most weather-protected area of the island — providing cover with reeds and a variety of nutritious food — being located in the north. The nearest sources of fresh water are in 2.5–3 km from the coast of the estuary. In general, the average distance between water crates on the spit is 0.9 km. Analysis of the permanent trails system of the island showed that 45 % of water resources are intensively used by ungulates, and 22 % have no visible trails.