Dissimilar home range estimates for black rhinoceros Diceros bicornis cannot be used to infer habitat change

Linklater, Wayne L.; Plotz, Roan; Kerley, Graham I. H.; Brashares, Justin S.; Lent, Peter C.; Cameron, Elissa Z.; Law, Peter R.; Hitchins, Peter

doi:10.1017/s0030605309990986

Cited by 8 publications

(21 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…; Linklater et al . ). The mechanism of density dependence is thus through mortality that is associated with increased social interactions rather then resource limitations.…”

Section: Discussionmentioning

confidence: 97%

Density-dependent regulation of the critically endangered black rhinoceros population in Ithala Game Reserve, South Africa

2013

View full text Add to dashboard Cite

Ensuring the persistence of populations of endangered species requires an understanding of, and response to, the causes of population declines. Species occurring in small populations are vulnerable to stochastic problems that are environmental, demographic, or genetic in nature and can reduce survival as much as the deterministic threats of habitat degradation. Critically endangered black rhinoceros (Diceros bicornis) populations declined throughout Africa since 1960, with numbers steadily increasing at a continental level, but remaining lower than three generations ago. However, size, demographics, trends, and factors affecting these, are poorly known. We used 18 years (1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008) of long-term sightings data from Ithala Game Reserve, KwaZulu-Natal, South Africa, to determine population estimates, growth rate and fecundity over time, as well as sex and age structure and age-specific probabilities of survival. Calf survivorship between the ages of 0 and 1 year was 74% for females and 94% for males. Age-specific survivorship for both sexes was significantly higher from yearling to subadult ageclasses (1-6 years) than for adults (7-30 years). The most frequent cause of mortality was attributed to unknown causes while fighting injuries was recorded as the second most common cause of mortality, particularly among subadult and adult males. There was no significant difference in the sex ratios at birth, although the proportion of females in the population was 0.58. There was strong evidence for density-dependent regulation, with density in conception year a key driver of population performance (birth rate). The population does not appear to be at ecological carrying capacity; however, social effects are delaying conception. To mitigate density-dependent social effects, we recommend an adaptive management strategy of pre-selecting individuals for removal from the reserve, so as to maintain stability in the social organization of the population.

show abstract

“…; Linklater et al . ). The mechanism of density dependence is thus through mortality that is associated with increased social interactions rather then resource limitations.…”

Section: Discussionmentioning

confidence: 97%

Density-dependent regulation of the critically endangered black rhinoceros population in Ithala Game Reserve, South Africa

2013

View full text Add to dashboard Cite

show abstract

“…Home range data, therefore, is relied on for conservation planning and monitoring efforts towards species recovery. However, the reliability of home range size estimates and their usefulness as a conservation tool has been eroded by the tendency for studies to ignore minimal data requirements and use dissimilar techniques that prevent meaningful inter-study comparisons [ 2 , 3 ]. There have been, therefore, recent calls for studies to address sources of error in home range methodology and interpretation [ 1 , 4 ].…”

Section: Introductionmentioning

confidence: 99%

Standardising Home Range Studies for Improved Management of the Critically Endangered Black Rhinoceros

et al. 2016

Self Cite

View full text Add to dashboard Cite

Comparisons of recent estimations of home range sizes for the critically endangered black rhinoceros in Hluhluwe-iMfolozi Park (HiP), South Africa, with historical estimates led reports of a substantial (54%) increase, attributed to over-stocking and habitat deterioration that has far-reaching implications for rhino conservation. Other reports, however, suggest the increase is more likely an artefact caused by applying various home range estimators to non-standardised datasets. We collected 1939 locations of 25 black rhino over six years (2004–2009) to estimate annual home ranges and evaluate the hypothesis that they have increased in size. A minimum of 30 and 25 locations were required for accurate 95% MCP estimation of home range of adult rhinos, during the dry and wet seasons respectively. Forty and 55 locations were required for adult female and male annual MCP home ranges, respectively, and 30 locations were necessary for estimating 90% bivariate kernel home ranges accurately. Average annual 95% bivariate kernel home ranges were 20.4 ± 1.2 km2, 53 ±1.9% larger than 95% MCP ranges (9.8 km2 ± 0.9). When home range techniques used during the late-1960s in HiP were applied to our dataset, estimates were similar, indicating that ranges have not changed substantially in 50 years. Inaccurate, non-standardised, home range estimates and their comparison have the potential to mislead black rhino population management. We recommend that more care be taken to collect adequate numbers of rhino locations within standardized time periods (i.e., season or year) and that the comparison of home ranges estimated using dissimilar procedures be avoided. Home range studies of black rhino have been data deficient and procedurally inconsistent. Standardisation of methods is required.

show abstract

“…Our understanding of the spatial ecology of black rhinos are hampered by methodological inconsistencies across location studies and a disregard for sources of location error (Linklater et al, 2010a;Plotz et al, 2016). Accurate location estimates are important because they provide greater insights into the ecological needs and the spatial structure of black rhino populations (e.g.…”

Section: Triangulation Errormentioning

confidence: 99%

“…Inaccurate, non-standardized location data have the potential to mislead black rhino population management (see Linklater et al, 2010a;Plotz et al, 2016). Thus, assessing and reporting on known errors in radio-telemetry location studies (e.g.…”

Section: Conservation Implicationsmentioning

confidence: 99%

“…Black Rhino Range Expansion Project, BRREP; Emslie, 2001;Linklater et al, 2012;Plotz, 2014;Hayward et al, 2017). Our experimental population consisted of 14 adult (>7 years; Law & Linklater, 2015) female rhinos who received horn-implanted radio transmitters (VHF) from March 2007 to October 2008 as part of a larger study of black rhino population dynamics (see Plotz & Linklater, 2009;Linklater et al, 2010a;Plotz, 2014;Plotz et al, 2016).…”

Section: Study Area and Populationmentioning

confidence: 99%

See 1 more Smart Citation

Too Close and Too Far: Quantifying Black Rhino Displacement and Location Error During Research

Plotz

Grecian

Kerley

et al. 2017

African Journal of Wildlife Research

Self Cite

View full text Add to dashboard Cite

Dissimilar home range estimates for black rhinoceros Diceros bicornis cannot be used to infer habitat change

Cited by 8 publications

References 7 publications

Density-dependent regulation of the critically endangered black rhinoceros population in Ithala Game Reserve, South Africa

Density-dependent regulation of the critically endangered black rhinoceros population in Ithala Game Reserve, South Africa

Standardising Home Range Studies for Improved Management of the Critically Endangered Black Rhinoceros

Too Close and Too Far: Quantifying Black Rhino Displacement and Location Error During Research

Contact Info

Product

Resources

About