Breeding Population Dynamics and Conservation of Whiskered Tern Chlidonias Hybrida in Italy

27 Mar Breeding Population Dynamics and Conservation of Whiskered Tern Chlidonias Hybrida in Italy

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Abstract

E’ stata effettuata una revisione e una sintesi delle informazioni disponibili su distribuzione e consistenza della popolazione nidificante dalla prima nidificazione avvenuta nel 1939 sino al 2005 evidenziando i maggiori fattori limitanti per la popolazione e gli effetti positivi conseguenti al ripristino di zone umide attraverso l’applicazione di misure agroambientali comunitarie. 

English Abstract

Breeding population dynamics and conservation of Whiskered Tern Chlidonias hybrida in Italy – On the basis of bibliographical data and unpublished information, the dinamics of the breeding population in Italy from 1939 until 2005 can be summarised as follows: 1939-1971 – regular breeding started in 1939 in a freshwater wetland in the province of Bologna (70-80 breeding pairs) and continued in the 50’s and 60’s in other five wetlands in the same province (100-300 breeding pairs); 1972-1986 – increase of the breeding population and of the breeding sites in Modena, Ferrara and Ravenna provinces; about 400 breeding pairs at the beginning of 80’s; 1987-1995 – decrease of the breeding population (about 300 pairs); 1996-2005 – minimum values of the breeding population recorded in 1996 and 1997 (about 200 pairs) then increase of the breeding population due to the colonisation of restored wetlands (about 600 pairs in 2004-2005); new breeding sites in the province of Pavia, Parma, Modena, Bologna, Ferrara and Ravenna and recolonisation of some of the most important breeding sites formerly abandoned. The spread of Coypu since 1987 resulted the most important limiting factor affecting the breeding population. From 1996 tha major part of the breeding population used some wetlands ecologically and/or temporarily less favourable for Coypu (> 5 hectares areas with dense floating vegetation, scarce or no reedbeds, water level < 60 cm and decreasing after May). The restoration of wetlands on arable lands carried out from 1994 in the framework of the Regulations EEC 2078/92 and EC 1257/99 (set-aside for 20 years to establish habitats for survival and reproduction of wild flora and fauna) increased the breeding population and the breeding sites.