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Assessing population trends and their underlying factors is critical to propose efficient conservation actions. This assessment can be particularly challenging when dealing with highly mobile, shy and nocturnal animals such as flying-foxes. Here we investigated the dynamics of hunted populations of Pteropus ornatus and P. tonganus in the Northern Province of New Caledonia. First, an ethno-ecological survey involving 219 local experts identified 494 flying-fox roosts. Current status was assessed for 379 of them, among which 125 were no longer occupied, representing a loss of 33% over ca. 40 years. Second, species-specific counts conducted at 35 roosts, and a sample of animals killed by hunters, revealed that the endemic species, P. ornatus, was dominant (68.5%). Between 2010 and 2016, 30 roosts were counted annually during the pre-parturition period. Roosts size averaged 1,425 ± 2,151 individuals (N = 180 counts) and showed high among-year variations (roost-specific CV = 37-162%). If we recorded significant inter-annual variation, we did not detect a significant decline over the 7-yr period, although one roost went possibly extinct. Population size of the two species combined was estimated at 338,000-859,000 individuals distributed over ca. 400 roosts in the Northern Province. Flying-foxes are popular game species and constitute traditional food for all communities of New Caledonia. Annual bags derived from a food survey allowed us to estimate harvesting rates at 5-14%. Such a level of harvesting for species with a 'slow' demography, the occurrence of poaching and illegal trade, suggest the current species use might not be sustainable and further investigations are critically needed.

Invasive alien species are a major cause of biodiversity loss globally, but especially on islands where high species richness and levels of endemism accentuate their impacts. The Red vented bulbul (Pycnonotus cafer), a tropical passerine bird that has been introduced widely across locations of high conservation value, is considered an extreme pest. It is currently expanding its range in New Caledonia, one of the world's biodiversity hotspots. Decisive recommendations on management strategies are required urgently to inform local managers and policy makers, but they should be based on quantitative local evidence, not just on expert opinion. The Red-vented bulbul is widely blamed for its impacts on biodiversity, especially through competition. We used data from 2,472 point counts to explore the abundance relationships between the Red-vented bulbul and 14 other species of bird. Our results revealed a negative relationship between the occurrence of the bulbul and the mean abundance of nine species, all native (or endemic, n = 3) to the New Caledonia archipelago. In contrast, the abundance of other introduced species such as Acridotheres tristis (Common myna), Passer domesticus (House sparrow) and Spilopelia chinensis (Spotted dove) were not affected by the Red-vented bulbul. Moreover, temporal trends in the abundance of impacted species suggest that the Red-vented bulbul may cause niche contractions rather than mortality for native species in man-modified habitats. Monitoring and control of the Red-vented bulbul is recommended to prevent on-going impacts on native bird communities throughout New Caledonia, and its impact on native bird communities elsewhere should be quantified.

BACKGROUND: Widespread but particularly incident in the tropics, leptospirosis is transmitted to humans directly or indirectly by virtually any Mammal species. However, rodents are recognized as the most important reservoir. In endemic regions, seasonal outbreaks are observed during hot rainy periods. In such regions, hot spots can be evidenced, where leptospirosis is "hyper-endemic", its incidence reaching 500 annual cases per 100,000. A better knowledge of how rodent populations and their Leptospira prevalence respond to seasonal and meteorological fluctuations might help implement relevant control measures. METHODOLOGY/PRINCIPAL FINDINGS: In two tribes in New Caledonia with hyper-endemic leptospirosis, rodent abundance and Leptospira prevalence was studied twice a year, in hot and cool seasons for two consecutive years. Highly contrasted meteorological situations, particularly rainfall intensities, were noted between the two hot seasons studied. Our results show that during a hot and rainy period, both the rodent populations and their Leptospira carriage were higher. This pattern was more salient in commensal rodents than in the sylvatic rats. CONCLUSIONS/SIGNIFICANCE: The dynamics of rodents and their Leptospira carriage changed during the survey, probably under the influence of meteorology. Rodents were both more numerous and more frequently carrying (therefore disseminating) leptospires during a hot rainy period, also corresponding to a flooding period with higher risks of human exposure to waters and watered soils. The outbreaks of leptospirosis in hyper-endemic areas could arise from meteorological conditions leading to both an increased risk of exposure of humans and an increased volume of the rodent reservoir. Rodent control measures would therefore be most effective during cool and dry seasons, when rodent populations and leptospirosis incidence are low.