The conservation value of paddock trees for birds in a variegated landscape in southern New South Wales. 2. Paddock trees as stepping stones

摘要

The use of paddock trees as stepping stones by birds was assessed in a grazing landscape in southern New South Wales, Australia. A total of 70 paddock tree sites was surveyed for 20 min each in the morning, and 36 sites were surveyed again in the afternoon in March 2000. During the surveys, the presence, direction of arrival, and direction of departure to and from sites was recorded for each bird. A stepping stone effect of paddock trees was examined in two ways: (1) by analysing the arrival and departure direction of birds relative to surrounding vegetation cover, and (2) by analysing the departure direction of birds relative to their arrival direction. An arrival direction was obtained for 150 independently acting groups of birds, and a departure direction was obtained for 203 independently acting groups of birds. Both arrival and departure direction were obtained for 87 independently acting groups. Foliage-foraging birds tended to follow relatively densely vegetated areas. There was some indication that granivores and nectarivores also preferred to move along densely vegetated areas. This trend was absent for open-country species. All groups of birds examined tended to return to their place of origin or move in the opposite direction of their arrival. This trend was most pronounced for nectarivores and the foliage-foraging White-plumed Honeyeater (Lichenostomus penicillatus), and less pronounced for open-country species and parrots. The results are discussed in relation to the biology and ecology of the various species of birds. We conclude that paddock trees have the potential to enhance landscape connectivity by acting as stepping stones to assist movement. This further highlights their conservation value as demonstrated in the first paper of this series.