Antioquia Brushfinch Atlapetes blancae is a recently rediscovered Colombian microendemic species with a restricted distribution. Although the species might use a variety of habitats, current information suggests that it is a shrubland specialist. It is categorised as “Critically Endangered” because due to habitat loss its population has been estimated to be smaller than 50 individuals. Such estimates are based on indirect measurements of its population and assumptions regarding its restricted range/habitat. We provide the first direct population estimates and adult sex ratio for seven localities, using mark-resighting techniques. Individuals were captured using mist-nets, bled, and colour banded. Subsequently, we performed censuses along transects to record banded and non-banded individuals. Population estimates were obtained using the classic closed population mark-resighting model. In addition, we used the abundance–area relationship to estimate population size at other sites where the species has been previously recorded. Finally, individuals were sexed by amplifying the Z and W-linked Chromo-Helicase DNA-binding gene (CHD) genes. In total, we banded 55 individuals at four locations. Summarising across the seven sampled localities, we found that the population is most likely composed of 109 individuals in the 122 ha sampled. Based on the abundance–area relationship, we estimated that the population of Antioquia Brushfinch could be as large as 405 individuals in 322 ha of suitable habitat. We found that male/female sex ratio was 0.45 (95% confidence interval [CI] 0.32–0.6) and that it was not significantly biased. Our results suggest that the population of Antioquia Brushfinch is at least eight times larger than suggested by secondary information. We found that populations are properly structured at least regarding sex ratio, although we caution for further research on sex biases of immature and juvenile individuals. We recommend that future studies should focus on population trends and the impact of habitat transformation on the demography of this iconic species.

Southern elephant seals Mirounga leonina within the Kerguelen province disperse between Marion Island (MI), Iles Crozet (IC) and Iles Kerguelen (IK) despite the high site fidelity characteristic of this species. From 1987–2002, 199 IC individuals, or 11.63% of the tagged population there, were resighted at MI. Resights of IC seals at MI peaked during the juvenile moult and seals aged 0–2 represent 66% of all resights made. Equal numbers of male and female seals (all age classes) were dispersing. Dispersing breeding females (n = 22, on 33 occasions) outnumbered dispersing breeding males (n = 6, on 16 occasions), after initially emigrating from IC to MI as juvenile seals (natal dispersal). Greater male-mediated gene flow was ultimately attained due to the polygynous mating system and some extremely successful males. Of 132 seals fitted with satellite-relay data loggers at MI, six hauled out at IC and three at IK. Two of the seals which migrated to IC were born at MI; all others were unmarked males likely to be native to IC or IK. Dispersal should ideally be considered when assessing vital rates for southern Indian Ocean elephant seal populations.