| Popis: |
Low-intensity tropical agro-ecosystems may be of high conservation value. However, identifying appropriate strategies for managing tropical ~ountryside for biodiversity is contentious. Bengal Florican Houbaropsis bengalensis is a globally threatened bustard restricted to the Indian subcontinent and Indochina. Within Indochina floricans are characteristic of low-intensity grassland agro-ecosystems typified by rice cultivation and burning. Surveys during 2005/06 and 2006/07 showed the importance ofgrasslands surrounding the Tonie Sap lake, Cambodia, for Bengal Florican, producing estimates of approximately 830 adult birds, at least 60% ofthe global population. However, analysis of remotely-sensed habitat classifications show that grassland cover declined by 53-66% between 1995/96 and 2006 owing to agricultural abandonment and, more recently, intensification of rice cultivation. Both processes reduce habitat suitability for Bengal Florican. Predictive models (using multi-model inference techniques applied to field survey data) suggest that florican distribution is limited by human activity outside areas targeted by conservation-outreach schemes, where florican abundance is now highest. This reduces model transferability between regions and I suggest such variation in species density can limit transferability of predictive distribution models generally. Comparing habitat between male display locations and random points showed agricultural activity in grasslands, particularly annual burning, provides suitable habitat for males within leks. Such tolerance of low-intensity human activity provides support for recent community-conservation initiatives. Radio telemetry studies indicate that burning also maintains the heterogeneity essential for the contrasting breeding-season requirements of male and female florican resulting from the species's polygynous breeding biology. However, less than one-third of t~gged females appeared to nest within leks, suggesting that other areas may be important for breeding and that conservation activities should not be restricted to leks. Further research must focus on female autecology and how best to maintain suitable grassland structure, for nesting female and displaying male florican, without alienating existing low-intensity users of the grasslands. |
