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ABSTRACTHedgehogs (Erinaceous europaeus), rabbits (Oryctolagus cuniculus) and possums (Trichosurus vulpecula) were 93.4% of 1390 mammal carcasses counted during 92 trips along a 63.2 km route, 2009–2014, through peri-urban and farmland habitats. Pukeko (Porphyriomelanotus) and swamp harriers (Circus approximans) constituted 29% of the 466 bird road-kill. Comparisons indicate the recovery of hedgehog and rabbit populations from declines to 2005 and 2009, respectively, and the increased suppression of possum populations, consistent with disease and pest control trajectories. Road-kill density was spatially and temporally aggregated. Seasonal peaks reflected species-specific periodicity in breeding and dispersal. Carcass densities varied positively with traffic volume and did not asymptote with increasing traffic up to 25,000 vehicles per day. Kill rates per vehicle were maintained at the highest traffic volumes. Busier roads were not avoided by wildlife and could be substantial demographic sinks and barriers to their spread. We discuss the implications for wildlife management and conservation.

The “extinction of [ecological] experience” is a concern for children in urban centres. Urban environments, traditionally the refuge of exotic human-commensal species, are being increasingly colonised by native species. We used a native bird as a focal species for integrating urban biological research and environmental education (EE) in conservation. We tested whether incorporating biological researchers into classroom teaching and hands-on experiences with radio-telemetry of wild birds increased wildlife knowledge, environmental awareness and intentions to act amongst children from local schools. We found no significant increases in knowledge after our EE programme. However, those children who participated in exercises with researchers in local green space demonstrated a greater level of nature awareness than groups who participated in the schoolyard, and retained this level three months after the programme completion. We illustrate the importance of incorporating biological research in conservation education in urban centres.

Abstract:Fighting and accidental injury commonly cause black rhinoceros (rhino; Diceros bicornis) death after release. Smaller reserves and higher conspecific density after release (release density) might increase a rhino's encounter rate with hazards like fenced boundaries and conspecifics. We conducted a science-by-management experiment on the influence of reserve size and release density on rates of movement, association, and injury and death amongst 39 black rhinos during the first 100 days after their release into 4 Namibian and 8 South African reserves ranging in size from 670 ha to 45,000 ha. Association rates were negatively related to reserve size and positively correlated with release density. There was also a negative relationship between the proportion of the reserve traversed by individual rhinos and reserve size. In reserves =18,000 ha association rates were consistently zero but became elevated in reserves =11,500 ha and at release densities =9 km2/rhino. Daily displacement did not increase with increasing reserve size >8,500 ha but in smaller reserves daily displacements indicated higher encounter rates by released rhinos with fenced boundaries. Three rhinos received fight-related injuries requiring intervention and 2 of 4 deaths were fight-related. All injuries and 3 deaths occurred in reserves =11,500 ha. Model selection based on Akaike's second-order Information Criterion indicated that the parameter release density alone best explained mortality risk. Traditionally considered risk factors, rhino sex, age, and presence of resident conspecifics, were superseded by the risk posed by releases into smaller reserves. Reserves =11,500 ha and release densities =9 km2/rhino pose an increasing risk to rhino survivorship and so larger reserves and lower densities than these should be favored as release sites.

Animal escape behaviour in response to aircraft could influence the accuracy and precision of aerial estimates of population size but is rarely investigated. Using independent observers on the ground and in the air, we recorded the behaviour of 17 groups, including 136 individually marked horses (Equus caballus), during a helicopter count in New Zealand's Kaimanawa Mountains and compared the helicopter count with a ground-based mark-resight estimate in the same area (20.5 km2). The helicopter induced running and changes in group size and composition in all horse groups that travelled from 0.1 up to 2.75 km before leaving the ground-observer's view. One-tenth of marked horses were not counted and a quarter counted twice. The possible double-counting of a further 23 (17%) could not be confirmed because only two of the three observers' records concurred. Thus, the helicopter count over-estimated the marked sub-population by at least 15% and possibly by up to 32%. The helicopter count (228 horses) was 16.9% larger than the mark-resight estimate (195, 95% CI = 157-234). We identify the characteristics of the helicopter count that stimulated horse escape behaviour and discuss how it should be considered in the design of aerial population-estimate methods.

Among mammals, non-offspring nursing is the most extreme form of communal parenting. This is because lactation is the most energetically costly part of parental investment (Clutton-Brock, 1991; Packer, Lewis & Pusey, 1992). Non-offspring nursing is most common in species characterized by large litters and small kin groups (Packer et al., 1992; e.g. lions Panthera leo: Pusey & Packer, 1994). Although non-offspring nursing has also been reported in monotocous species (e.g. water buffalo Bubalus bubalus, Murphey et al., 1995; African elephant Loxodonta africana: Dublin, 1983; Lee, 1987; Indian elephant Elaphus maximus: MacKay, 1973; Rapaport & Haight, 1987; fallow deer Cervus dama: San José & Braza, 1993) it is almost always associated with reproductive errors (Riedman, 1982) such as milk theft or exclusive adoption (Packer et al., 1992). However, simultaneous non-offspring nursing in monotocous species has been reported in some bat species (e.g. McCracken, 1984; Eales, Bullock & Slater, 1988), African elephants (Lee, 1987), and captive Indian elephants (Rapaport & Haight, 1987). Recent research, however, suggests that nutritive non-offspring nursing in African elephants is rarer than previously thought as most reported instances were probably non-lactating juveniles allowing infants to suckle (Lee & Moss, 1986; Lee, 1987, 1989).

Adaptive theory predicts that mothers would be advantaged by adjusting the sex ratio of their offspring in relation to their offspring's future reproductive success. Studies investigating sex ratio variation in mammals have produced notoriously inconsistent results, although recent studies suggest more consistency if sex ratio variation is related to maternal condition at conception, potentially mediated by changes in circulating glucose level. Consequently, we hypothesized that change in condition might better predict sex ratio variation than condition per se. Here, we investigate sex ratio variation in feral horses (Equus caballus), where sex ratio variation was previously shown to be related to maternal condition at conception. We used condition measures before and after conception to measure the change in condition around conception in individual mothers. The relationship with sex ratio was substantially more extreme than previously reported: 3% of females losing condition gave birth to a son, whereas 80% of those females that were gaining condition gave birth to a son. Change in condition is more predictive of sex ratio than actual condition, supporting previous studies, and shows the most extreme variation in mammals ever reported.