The ecology of the song thrush, Turdus philomelos Br., in Ireland

Over the last 30 years, western European Song Thrush populations have declined with the steepest decline recorded on British farmland. Changes in agricultural practices have been implicated in these population declines. Ireland is an agriculturally dominated landscape but changes in agriculture here have occurred on a relatively slower rate and scale. Little is known about the ecology of the Song Thrush in Ireland, even though it is not classified as a species of conservation concern here. Some decline is thought to have occurred but the current breeding population appears to be stable and widespread. In light of these facts, this study investigated various aspects of Song Thrush ecology in relation to the Irish landscape from 2001-2003. The breeding season extended from mid March to late June, where mean clutch size was 4.1 and number of fledglings was 3.7. There were very few third broods. Daily nest survival rates were calculated for egg stage 0.9362, incubation stage 0.9505 and nestling stage 0.6909. Most nest failures were due to avian predation at both egg and chick stages. Most nests were located 1.3 -2.4m from the ground at trees, bushes or hedgerow. Clutch size was significantly higher on farmland than garden & parkland and woodland, and the number of fledglings was significantly lower in nests in trees than hedgerow and bush sites. Daily nest fail rates were significantly higher at tree sites and partly concealed nests. Nesting areas had significantly denser vertical vegetation than non-nesting areas. Mercury and the organochlorine HEOD were the most common contaminants in Song Thrush eggs and livers. However concentrations and occurrence were low and of no apparent biological or ecological concern. The presence of breeding Song Thrushes was influenced by mixed surrounding farmland, the absence of grass surrounding farmland, ditches especially wet ones, tall dense vegetation and trimmed boundaries. Song Thrush winter densities were predicted by ditches, with wet or dry, low thin vegetation and untrimmed boundaries. Winter densities were almost double that of the breeding season, probably due to the arrival and passage of migrating Song Thrushes through the country, especially in November. Changes in Irish agriculture did not differ significantly in areas of Song Thrush breeding population stability and apparent decline during 1970 1990. Even though the current breeding population heavily uses farmland, woodland, human and scrub habitats are more preferred. Nevertheless no farmland habitat was avoided, highlighting a positive relationship between breeding Song Thrushes and Irish agriculture. This appears to be in contrast with findings between breeding Song Thrushes and British agriculture. Theses findings are compared with other studies and possible influences by agricultural intensification, climate, latitude and insular syndrome are discussed. Implications for conservation measures are considered, especially for areas of decline. Even though Song Thrushes are currently widespread and stable here, future environmental consequences of longer-term changes in Irish agriculture and perhaps climate change remain to be seen.

Comparing impacts of new cropping systems on biodiversity in traditional rural China

This study selected six geographically-similar villages with traditional and alternative cultivation methods (two groups of three, one traditional and two alternatives) in two counties of Henan Province, China—a representative area of the Huang-huai-hai Plain representing traditional rural China. Soil heavy metal concentrations, floral and faunal biodiversity, and socio-economic data were recorded. Heavy metal concentrations of surface soils from three sites in each village were analysed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS, chromium, nickel, copper, cadmium, and lead) and Atomic Absorption Spectrophotometer (AAS, zinc). The floral biodiversity of four land-use types was recorded following the Braun-Blanquet coverage-abundance method using 0.5×0.5m quadrats. The faunal biodiversity of two representative farmland plots was recorded using 0.3×0.3m quadrats at four 0.1m layers. The socio-economic data were recorded through face-to-face interviews of one hundred randomly selected households at each village. Results demonstrate different cultivation methods lead to different impact on above variables. Traditional cultivation led to lower heavy metal concentrations; both alternative managements were associated with massive agrochemical input causing heavy metal pollution in farmlands. Floral distribution was significantly affected by village factors. Diverse cultivation supported high floral biodiversity through multi-scale heterogeneous landscapes containing niches and habitats. Faunal distribution was also significantly affected by village factor nested within soil depth. Different faunal groups responded differently, with Acari being taxonomically diverse and Collembola high in densities. Increase in manual labour and crop number in villages using alternative cultivation may positively affect biodiversity. The results point to the conservation potential of diverse cultivation methods in traditional rural China and other regions under social and political reforms, where traditional agriculture is changing to unified, large-scale mechanized agriculture. This study serves as a baseline for conservation in small-holding agricultural areas of China, and points to the necessity of further studies at larger and longer scales.