by Alexei SEVERTSOV, Dr. Sc. (Biol.), Biological Department of the Moscow State University named after M. Lomonosov, Anna SHUBKINA, Cand. Sc. (Biol.), Institute of Problems of the Ecology and Evolution named after A. Severtsov Why this or that animal falls prey to predator? The observations in natural environment show that it is rather difficult to estimate reasons why the particular animal becomes the prey. Predators are unable to catch any animal suitable for them in size, not each potential object is available. Consequently, there exists, as specialists say, the "selective removal", which means the natural selection, accomplished by predators. WHO IS LUCKIER THAN A CHEETAH? Field studies are associated with numerous challenges. Besides, classical field methods are rather inefficient. The first problem for the scientists is estimation of the predator's hunting success. In other words, you should know an exact number of pursuits and their results. Normally, such observations are carried out in winter by tracking in snow, i.e., by way of studying attacks by traces left by the animal. It is a labor-intensive and arduous task, since predators are able to run some tens of kilometers daily, including places difficult of access, while a biologist needs to count all attempts to catch the prey to get reliable biological data. In addition, winter is the hard time for herbivorous animals, when they can become totally helpless. That's why, there is a probability of incorrect interpretation of real elimination reasons. Often it is impossible to use technical devices-predators could be afraid of snowtractors following their стр. 11 tracks: active observations may affect their behavior and spatial distribution. Therefore, assessment of hunt success is usually rough. It has been established that efficient pursuits occasionally reach 50 percent of the total number of attempts. For instance, a cheetah-the fastest of big predators-succeeds only in ... Читать далее