ИСТИНА

Our current research is a fragment of the work that has been carried out for more than 50 years in the Laboratory of behavior physiology and genetics. It is concerned with comparative investigations on cognitive abilities of birds from Corvidae family. Usually, we deal with the birds in laboratory conditions. However, field data are also of great importance because they improve our knowledge on the species by referring to natural bird behavior in their environmental. Over last three years, we have been studying the cognitive abilities of the large-billed crows in their natural habitats. The features of crow behavior living wild on the Shickotan Island make them good subjects. On the small island (only 25 km across) there are two fish farms which are the sources of fish guts. A regular supply of extra food led to artificially large numbers of crows in the area and also encourages their aggressive behavior to each other. On the other hand, birds are very tolerant to people and their local activities. They used aluminum wire to build their nests. When the delays happen on fishing farms, crows are faced a problem – where and how to get food enough. To solve it birds demonstrate very innovative behavior using a wide variety of methods many of which are not a part of their behavioral repertoire. So, crows steal food from kitchens, eggs from hen houses and nests of marine birds. They are not afraid of domestic animals at all and swipe their food on the spot. They open tin cans, crash muscle seashells by dropping them on roads and roofs, dig up the earth to get potatoes and parrots. While observing such behavior one question which arises is how those features of crow behavior and their skills are transmitted though the crow population? The aim of present work was to find out whether crow youngsters are able to learn new skills from their parents. The experiments were carried out during the crows’ breeding period, from early May to the end of September, when each bird’s pair in occupies and protects their nesting territory. A total of 14 crows were used as subjects. It was three families, which of them consisted of 2 parents who had 2, 2 and 4 youngsters correspondently. In order to find out whether crow youngsters are able to learn new skills from their parents, three parents (males) from different families were trained to get a bait opening one of four boxes differing in color. Four wooden boxes were presented every day. Only the red box was reinforced. During experiment the position of boxes varied quasi-randomly. The criterion was no 5 correct choices successively. 13 – 15 trials were necessary for males to reach the criteria. It took 7 and 8 trials for their female partners to learn the skill. At that time their youngsters were in nests and could not see how their parents had been trained. To identify youngsters they had been marked by color rings. At about 60 days old youngsters started following their trained parents through the nest territory. Every day (during one month) the youngsters came with their parents, so they could see what the parents were doing to obtain food from boxes. The parents opened the red box and used the obtained food to feed their youngsters. Until they were about 90 days old, they didn’t use to try obtaining food itself, they only had been bagging it from parents. At 91 - 92 days old youngsters’ behavior had completely changed. They started flying on its own and attempted to open boxes and get food without assistance from their parents. In the first trial all youngsters had been able to open boxes but failed to choose the red one. Then they had learned to choose red box by trials and errors and reached the criteria as fast/ quickly as their parents: it took 7 – 13 trials. Conclusions: 1. The crow youngsters are able to learn new skills observing what their parents are doing. It seems they use the same mode of social learning as chimpanzee infants, so-called “Education by master-apprenticeship”. Firstly, crow youngsters have prolonged exposure to adult behavior based on the parents- youngsters bond. Secondary, lack of active teaching (no formal instruction, and no positive/negative feedback from the parents). Thirdly, the youngsters’ intrinsic motivation to copy the parent’s behavior. Through education, crows seem are able to pass knowledge and skills from one generation to the next. 2. During experiment the other adult crows were around and could observe how the trained crows obtained food as well. In contrast, none of them tried to open boxes. On the basis of this study, we drew a conclusion that during breeding period the special skills are transferred through the family only, i.e. from a trained crow’s male to its female partner and then to their youngsters.