Survival of theAfrican white‐backed vultureGyps africanusin north‐easternSouthAfrica

Abstract

Old World vultures are in decline across their entire range. Although critical for the formulation of effective conservation measures, neither survival nor movement patterns of African vultures are adequately known. This paper presents survival and movement data on the African white‐backed vultures (Gyps africanus) from South Africa. Survival estimates were modelled on resightings of tagged vultures. Birds were captured en masse and resighted between November 2005 and December 2010. A total of 93 adult and subadult birds were fitted with uniquely numbered patagial tags, which were resighted 3707 times(mean of 39.8 resightings per bird). The programme MARK was used to estimate survival. The best model was one where survival and recaptures varied only with time (e.g. year). However, owing to the fading (illegibility) of tags in later years, the relationship with time is probably spurious. The second best model was one where survival and recaptures varied with age and time. Annual survival estimates increased from 85.2% in second‐year birds to 99.9% in adults. This corresponds well with the survival of two other Gyps vultures that have been studied to date and underscores the point that additional mortality of adults in these long‐lived species will result in rapid population declines.

Effect of rehabilitation on survival rates of endangered Cape vultures

“…These assumptions are: (1) every marked animal present in the population at time ( i ) has the same probability of recapture ( pi ); (2) every marked animal in the population immediately after time ( i ) has the same probability of surviving to time ( i + 1); (3) marks are not lost or missed; (4) all samples are instantaneous, relative to the interval between occasion ( i ) and ( i + 1), and each release is made immediately after the sample. The loss of tags from birds have been reported from other recent studies using similar patagial tags (Monadjem, Botha & Murn, 2012 a ; Monadjem et al ., 2012 b ), and this is thought to be the case in this study as well. Since there is no reason to suspect that the rate of tag loss would differ between rehabilitated and wild‐caught birds, any errors in estimation of survival rates should equally affect both groups.…”

Using Africa's protected area network to estimate the global population of a threatened and declining species: a case study of the Critically Endangered White‐headed Vulture Trigonoceps occipitalis

“…; Monadjem et al. ) and used the following age‐specific annual survival parameters: Juvenile (1st year) 70%, Immature (2–4 years) 92%, Adult (5+ years) 98%. Corresponding population age‐class proportions based on road transect data (C. Murn, unpubl.…”

“…For each scenario the census population was calculated, as above, by adding an additional 0.46 immature and nonbreeding adults per breeding adultresulting in census populations of 12, 29, 58, and 61 birds. There are no survival and mortality data for White-headed Vultures, so we utilized data from other vulture species (Piper et al 1999;Monadjem et al 2012) and used the following agespecific annual survival parameters: Juvenile (1st year) 70%, Immature (2-4 years) 92%, Adult (5+ years) 98%. Corresponding population age-class proportions based on road transect data (C. Murn, unpubl.…”

Revisiting the Effect of Capture Heterogeneity on Survival Estimates in Capture-Mark-Recapture Studies: Does It Matter?

“…While some vultures visited this site regularly, others were only found there occasionally, thus creating strong individual heterogeneity in resighting probabilities (Figure 3). See [34] for more details.…”