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How species diversity is determined is an old question in community ecology but is not yet well understood. Island biotas offer opportunities to address this issue. Here, the ant fauna was studied in five moderately isolated islands of Japan and compared with those in reference regions on the nearby main islands to assess whether ants' ecological characteristics affect their island colonisation success. Species that were more abundant in the reference regions were more frequently found on the islands, suggesting that ant communities on these islands are likely to have a nested subset structure. Species inhabiting both forests and open lands tended to occur more frequently in the study islands at least than those exclusively inhabiting forests, but this difference was not significant. In addition, nest sites and worker body size did not have significant effects on their occurrence in these islands. These results seem to suggest that the study islands as a whole offer various environments that support a variety of ant species with different ecological characteristics. It is suggested in this study that island size affects the species richness, as has often been reported. [ABSTRACT FROM AUTHOR]

The reproduction of the Western Marsh Harrier Circus aeruginosus in submerged and dried up thickets of French tamarisk Tamarix gallica at El Maleh Dam reservoir, Benslimane Province, Morocco, was studied through monitoring nests in three successive years (2017–2019). Systematic field investigation showed that the nests were concentrated exclusively in a narrow and shallow area upstream of the dam. The abundance of tamarisk is a determining factor in the breeding success of the Western Marsh Harrier at this site, by supporting the nests and giving them some protection from predation while the birds are close to agricultural fields, a favourable hunting ground. A study of individual broods revealed a relatively small clutch size (3.5 eggs per nest) and that incubation took 32 days on average. Compared with previous reports for this species elsewhere, the chicks fledged relatively early (33 or 35 days), but with a low fledgling success rate not exceeding 33.9%. The low fledgling success is partly attributable to the structure of the habitat, as the dense dry vegetation above the water level limits the movement of chicks out of nests yet favours the drowning of those that fall from the nest. Breeding success is influenced by a reduction in hunting territory caused by drops in the water level during periods of drought, poor climate conditions, and disturbance caused by human activities in the reservoir lake and riparian farmland. In addition to these environmental factors, nest failure due to nest destruction is related to the experience of the pairs in choosing the nesting site and their ability to weave the nest-building materials. Further study is needed on the characteristics of this highly specific habitat and its state of conservation, the reproduction of coexisting bird populations, and human activities around the breeding site. [ABSTRACT FROM AUTHOR]

We studied red-crowned parakeets (Cyanoramphus novaezelandiae) reintroduced onto Tiritiri Matangi Island, New Zealand from 2004 to 2006, in order to provide baseline information regarding nesting sites and nesting success of this population. We found 48 nests both in natural nesting sites and in nest boxes, in all three major habitat types on the island. Clutch size declined as the breeding season progressed, but laying date did not affect nesting success. This means that a breeding pair could fledge at least one young even from a small clutch laid late in the breeding season. Overall nesting success was 60%. Nesting success varied between breeding-seasons. Most of the 17 nesting attempts that failed did so during incubation. Redcrowned parakeets made use of a wide diversity of nesting sites and few sites were re-used, which suggests that suitable nest sites were not limiting. Overall, our results indicate that red-crowned parakeets are good candidates for reintroductions to areas lacking introduced predators, even during the early stages of revegetation. [ABSTRACT FROM AUTHOR]