This study evaluated the short-term hormonal and behavioural responses to capture and radio-collar fitting in free-ranging pampas deer (Ozotoceros bezoarticus). Twenty adult deer (eleven females and nine males) were captured in the South Pantanal wetland (Brazil) and equipped with VHF radio-collars (marked deer). Untreated adult deer of the same sex were randomly chosen as the control group (nine females and nine males). On the day following capture, an observer followed all deer for faecal collection and behaviour evaluation. Faecal samples were immediately refrigerated and frozen at-20°C within a maximum of 12 h. Faecal glucocorticoid metabolites (FGM) were measured using an 11-oxoaetiocholanolone enzyme immunoassay. A qualitative behaviour assessment and the consequences of capture were evaluated using pre-defined terminologies and scores. Flight distance was recorded using a range finder. FGM increased from 19-22 h after capture onwards and peak concentrations were five times (median) higher as the respective baseline values. FGM values of marked deer were significantly higher at 22-25 and 25-28 h compared with controls. Marked male but not female deer had significantly higher FGM values at 22-25 and 25-28 h compared with their baseline values. Marked deer were significantly more fearful, less sociable and defensive than controls. The absences of significant increases of FGM in the captured female deer may indicate that females are less prone to capture stress. The significantly more fearful, and less sociable and defensive patterns observed in marked deer may be relevant during capture of lactating females or in areas with high predator pressure.

The savannah enclaves (i.e. patches) in the southern Brazilian Amazonia are among the most threatened and poorly surveyed sites in Amazonia. As part of an extensive mammal survey, we set camera traps in three of these savannah enclaves. We obtained 23 independent records of pampas deer Ozotoceros bezoarticus, a medium sized Neotropical cervid that is strongly associated with open habitats and categorized as Vulnerable on the Brazilian Red List of threatened species. These savannah enclaves with confirmed populations of pampas deer lie outside the species’ previously presumed historical range and are at least 350 km from any known extant population. Together, these savannah enclaves add c. 4,000 km2 to the pampas deer's currently known range. The small pampas deer populations in these enclaves are probably isolated by a matrix of Amazon forest, raising questions about spatial genetic structure and meta-population dynamics, and making them vulnerable to local extinction. We highlight the need for further studies, particularly genetic, to assess the conservation status of these populations, the results of which could potentially inform management decisions in other areas of the heavily fragmented range of this species.