A Debreceni Déri Múzeum Évkönyve 2007 (Debrecen, 2008)

Természettudomány - Kövér László – Juhász Lajos: A dolmányos varjú (Corvus cornix L.) debreceni terjeszkedése

NAGYJ. 1952 A vörösfejű gébics legutolsó előfordulása Debrecenben. Aquila, 59/62. évf: 395-396. REICHHOLFJ. 1999 Települések ökológiája. Magyar könyvklub, Bp. 223 p. SÁTORI J. 1941/a A házi rozsdafarkú folytatólagos terjeszkedése Debrecenben. Aquila, 46/49. évf: 455-456. 1941/b Vörösvércse költése mesterséges fészekben. Debreceni Szemle, 1941.5:110-116. SÓVÁRGÓ M. 1943/a Hajnalmadár Debrecenben. Aquila, 50. évf: 406. 1943/b Újabb adatok a balkáni kacagógerle debreceni előfordulásához. Aquila, 50. évf: 405. SZEMADÁM GY. 2006 „Hithcock madarai" Budapesten. Madártávlat, 13/3:25. TAPFER D. 1978 A dolmányos varjú (Corvus comix) további és rendszeres fészkelése Budapest VIII. kerületében. Madártani tájékoztató, 1978. novdec: 39-41. 1985 A dolmányos varjak (Corvus cornix) fészkelése Budapest belső kerületeiben. Madártani tájékoztató, 1985. ápr.-júni.: 55-56. UDVARDYM. 1939 Balkáni kacagógerle Debrecenben. Aquila, 42/45. évf: 671-72. ZILAHI-SEBESSG. 1957 Hajnalmadár Debrecenben. Aquila, 63/64. évf: 303. László Kövér - Lojos Juhász Dr. THE SPREAD OF THE HOODED CROW (CORVUS CORNIX L.) IN DEBRECEN The urbanisation of birds has been simultaneous with the development of civilisations. The close proximity of man has provided some species with new opportunités of foraging and nesting. The hooded crow is one of the species that have realised and - owing to their high intelligence - soon seized the opportunities provided by towns. We extended our research to the whole town, but we conducted a systematic investigation primarily in the northern districts of Debrecen, which is home to a larger number of the species' urban population owing to the conditions of habitat. In the course of our investigation we discovered 11 active nests in 2006 and 12 ones in 2007. The nests were located on 8 different species of trees, always hidden on the tree top, at an average height of 13-14 metres. In 2007 we reached 5 nests with the help of a crane and managed to ring 8 fledglings in 2 nests in order to obtain further information about them. We have learnt that the urbanised individuals of the species choose a tree for nesting based on the qualities of the tree rather than its species, and they build a new nest every year. With 4-5 individuals in each nest, the northern district of the town has a sizeable crow population. This number does tremendous harm to the town's bird fauna, because during the nesting period other birds fall victim to nest robbing by crows. Other causes for concern are the noise made by crows and their increasingly frequent aggressive behaviour. We are to find a way of stemming their number in the future. With all this in mind, we consider it important to continue our research on the urbanisation process of the species and interfere if necessary.