In an environment that is in constant motion adaptive capacity is one of the primordial characteristics of living organisms. Many researchers have studied this issue, but nowadays the given research direction remains actual. Currently, in Moldova the following species of breeding prey birds can be encountered: European honey buzzard (Pernis apivorus), Short-toed snake eagle (Circaetus gallicus), Black kite (Milvus migrans), Western marsh harrier (Circus aeroginosus), Montagu’s harrier (Circus pygargus), Northern goshawk (Accipiter gentilis), Eurasian sparrowhawk (Acipiter nisus), Common buzzard (Buteo buteo), Lesser spotted eagle (Aquila pomarina), Common kestrel (Falco tinunculus) , Red-footed falcon (Falco vespertinus), Eurasian hobby (Falco subbuteo), Saker falcon (Falco cherrug), White-tailed eagle (Haliaeetus albicilla), Booted eagle (Aquila pennata), Long-legged buzzard (Buteo rufinus). From the above list some species Accipiter gentilis, Acipiter nisus, Buteo buteo and Falco tinunculus are more common, others, such as Falco cherrug , Haliaeetus albicilla , Aquila pennata are very rare and can be even absent from republic’s fauna for several years. For data collection were used two classic methods: transects and observation from fixed point. These data were used differentially depending on data that we wanted to collect, period and not least of habitat. Transect method consists in selection of certain route in an area previously established. This method was used to identify the nests. The fixed point observation method involves choosing a certain point in a certain area where observations will be made. This method was used to identify nesting pairs. During cold period of 2012-2015 were checked approximately 5,000 hectares of forest and 20,000 ha around the open land in different parts of the country, in order to identify nests of prey birds. These periods were chosen because the visibility in closed and semi-open land is higher. Later, during nesting season (April-June) the nests were checked again to determine their occupancy. In total they were identified and recorded using GPS 76 nests and at the second checking during nesting season it was detected that 39 out of 76 nests were occupied by various species of Falconiformes prey birds. As result of the study 11 species of diurnal prey birds were registered at breeding on the territory of the republic (tab. 1). Table 1. Prey bird species found at breeding in the republic during 2012-2015 Species No of occupied nests Falco tinnunculus Common kestrel 10 Falco cherrug Saker falcon 3 Falco subbuteo Eurasian hobby 9 Buteo buteo Common buzzard 7 Buteo rufinus Long-legged buzzard 2 Accipiter gentilis Northern goshawk 3 Accipiter nisus Eurasian sparrowhawk 1 Haliaeetus albicilla White-tailed eagle 2 Pernis apivorus European honey buzzard 2 Aquila pennata Booted eagle 1 Milvus migrans Black kite 1 The nests of Falco tinnunculus, Falco cherrug, Falco subbuteo and one nest of Buteo rufinus were found on electric poles, while the nest of other species were foung on trees at high altitude, most of them being located in woods on old oak and ash trees. The most common and widespread were the Common kestrel, Eurasian hobby and Common buzzard. We have to mention the high occurrence of Eurasian hobby in the last years, although the existing data show that it is a very rare species, that wasn’t recorded at breeding for many years. Among other rare species can be mentioned Saker falcon, White-tailed eagle, European honey buzzard, Booted eagle, included in the Red Book of Moldova (2015). It must be mentioned the presence of Long-legged buzzard in the southern and northern parts of the republic, which was recorded for the first time in 2012 (Ajder, Baltag….) The causes of change in the number of prey birds is due primarily to reducing of food base, accompanied by decreasing of suitable nesting places, because of the forest cutting, especially of old trees for commercial purpose, instead of sanitary cleaning of unhealthy or damaged trees. Another factor is the conventional farming practices with applications of pesticides, land processing with agricultural heavy technique, poaching, disturbance during breeding period etc. The work was performed within the fundamental project 15.187.0211F at the Institute of Zoology of A.S.M.