Papers by Wayne Linklater
Conservation Letters, 2018
New Zealand's policy to exterminate five introduced predators by 2050 is well-meant but warrants ... more New Zealand's policy to exterminate five introduced predators by 2050 is well-meant but warrants critique and comparison against alternatives. The goal is current or near-future technologies and resources. Its effects on ecosystems and 26 other mammalian predators and herbivores will be complex. Some negative out-comes are likely. Predators are not always and everywhere the largest impact on bio-diversity. Lower intensity predator suppression, habitat protection and restoration,and prey refugia will sometimes better support threatened biodiversity. The policy draws attention to where predators are easily killed, not where biodiversity values are greatest. Pest control operations are already contested and imposing the policy is likely to escalate those conflicts. While “high-profile,” a focus on predator eradication obscures the fact that indigenous habitat cover and quality continues to decline.Thus, the policy is flawed and risks diverting effort and resources from higher environmental priorities and better alternatives. Biodiversity conservation policies should be guided by cost-benefit analyses, prioritization schemes, and conservation planning in an adaptive management framework to deliver nuanced outcomes appropriate to scale- and site-specific variation in biodiversity values and threats. The success of biodiversity sanctuary-“spillover” landscapes, habitat restoration, and metapopulation management provide the foundation to build a better policy.
Frontiers in Ecology and the Environment, 2015
Comparisons of recent estimations of home range sizes for the critically endangered black rhinoce... more 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 km 2 , 53 ±1.9% larger than 95% MCP ranges (9.8 km 2 ± 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. Standardisa-tion of methods is required.
Actual observations of black rhinoceros predation are rarely reported and are limited to two inci... more Actual observations of black rhinoceros predation are rarely reported and are limited to two incidences involving subadults. Nevertheless, some authors attribute tail and ear deformities in up to 7.1% of some populations to predation attempts. In August 2008 we observed a mother with dependent c. 8month-old female black rhinoceros calf in Hluhluwe-iMfolozi Park, South Africa. The calf had a recently amputated tail, wounds to the anogenital region, right posterior flank and right side of the neck resembling a lion attack. Thirteen days later and on three subsequent occasions, the mother was sighted alone, suggesting that the calf had succumbed to its injuries. This incident provides evidence to suggest a link between attempted lion predation and tail amputation in black rhinoceros. Significantly, it implies that amputated tails and ears throughout Africa may represent failed depredation attempts and that calf predation may be more prevalent than previously appreciated. Predation is seldom considered in the management of black rhinoceros but should be when attributing cause to poor population performance of this critically endangered species.
PloS one, 2016
Comparisons of recent estimations of home range sizes for the critically endangered black rhinoce... more 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. ...
Http Dx Doi Org 10 1080 10871209 2015 961213, Mar 9, 2015
BioScience, 2004
Behavioral ecologists have advocated a greater role for behavioral research in conservation, and ... more Behavioral ecologists have advocated a greater role for behavioral research in conservation, and the contribution of behavioral study to conservation has increased dramatically. However, a review of the literature in the fields of behavioral ecology and ...
Wildlife Society Bulletin, 2002
... Wayne Linklater (right) is a Millennium Post-Doctoral Fellow at the Center for Reproduction o... more ... Wayne Linklater (right) is a Millennium Post-Doctoral Fellow at the Center for Reproduction of Endangered Species of the Zoological Society of San Diego (BS and MS in freshwater ecology, University of Canterbury; Ph.D. in ecology, 1999, Massey University, New Zealand). ...
Journal of Zoology, 1999
Among mammals, non-offspring nursing is the most extreme form of communal parenting. This is beca... more 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).
Animals, 2013
The North Island kākā (Nestor meridionalis septentrionalis), a threatened New Zealand native parr... more The North Island kākā (Nestor meridionalis septentrionalis), a threatened New Zealand native parrot, was successfully reintroduced to an urban sanctuary in Wellington, New Zealand. Conflict has recently begun to emerge with Wellington City residents due to tree damage caused by kākā sap foraging. Little is known about sap foraging behavior of kākā, and this study aimed to gain a greater understanding of this behavior, and to test hypotheses that sap feeding is predominantly a female activity and that one technique, forming transverse gouges through bark, may be restricted to adult kākā. We used instantaneous scan sampling to record the behavior of kākā during 25 60-100 minute observation periods at Anderson Park, Wellington Botanic Garden, and during 13 opportunistic observations of sap feeding kākā in Wellington City. Forty-one observations of sap feeding were made of 21 individually-identified birds. Sap feeding birds were predominantly young and, based on estimated sex, females were no more likely to sap feed than males (exact binomial test p = 0.868). Twenty of the 21 identified sap feeding kākā utilized supplementary feeding stations at Zealandia-Karori Wildlife Sanctuary. Kākā were observed defending sap feeding sites from tui (Prosthemadera novaeseelandiae) and conspecifics. Sap appears to be an important resource for kākā across sexes and life stages, and provision of supplementary food is unlikely to reduce sap feeding and tree damage in Wellington City.
Http Dx Doi Org 10 1080 03014220909510147, Feb 19, 2010
We compare the number of medium‐sized animals (between rat and dog‐size) killed on repeated count... more We compare the number of medium‐sized animals (between rat and dog‐size) killed on repeated counts along the same 1660 km of North Island highways in 1984, 1994 and 2005 with other counts going back to 1949. Elevenmammal and 14 bird species were recorded, but Australian possums (Trichosurus vulpecula), hedgehogs (Erinaceus europaeus) and rabbits (Oryctolagus cuniculus) predominated, and pukekos (Porphyrio porphyrio),
... Linklater WL. Centre for Biodiversity & Restoration Ecology, School of Biological... more ... Linklater WL. Centre for Biodiversity & Restoration Ecology, School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140, New [email protected]. Comment on: Behav Processes. 2007 Sep;76(1):1-13. ...
South African Journal of Wildlife Research, 2010
Facultative sex allocation theories predict that animals will bias their offspring's sex in respo... more Facultative sex allocation theories predict that animals will bias their offspring's sex in response to environmental cues. Biased sex ratios can be a problem when managing small populations in the wild or captivity. Using rainfall and calving records from Hluhluwe-iMfolozi Park in South Africa, we compared seasonal and annual rainfall with calving rates and sex of the calves. Between 1989-2004, 159 calves were sighted soon enough after birth to reliably attribute their conception to a particular season and year. Conceptions were strongly seasonal, with most (73.6%) occurring during rainy seasons and the remainder during dry seasons. Overall progeny sex ratio for the period 1989-2004 was 53.1% male. Mothers were more likely to be observed with male calves if they conceived during the wet season (57.3% male) than during the dry season (42.9% male) in accordance with the Trivers-Willard hypothesis. Similar numbers of conceptions that resulted in calves occurred during wet and dry years (52.2% of conceptions occurred during wet years). Mothers were more likely to raise male calves if they conceived during wet years (60.2% male) than during dry years (46.1% male). Removal of males from small populations might be particularly important after a sequence of wet years to facilitate greater population growth.
Reproduction, Fertility and Development, 2007
Many sex allocation mechanisms are proposed but rarely have researchers considered and tested mor... more Many sex allocation mechanisms are proposed but rarely have researchers considered and tested more than one at a time. Four facultative birth sex ratio (BSR) adjustment mechanisms are considered: (1) hormone-induced conception bias; (2) sex-differential embryo death from excess glucose metabolism; (3) sex-differential embryo death from embryo-uterine developmental asynchrony; and (4) pregnancy hormone suppression and resource deprivation. All mechanisms could be switched on by the corticoadrenal stress response. A total of 104 female rhinoceroses (Rhinocerotidae), translocated from 1961 to 2004 at different stages of gestation or that conceived soon after arrival in captivity, were used to test for a reversal in BSR bias as evidence for the action of multiple sex-allocation mechanisms. Translocation induced a statistically significant BSR reversal between early gestation (86% male births from 0 to 0.19 gestation) and mid-gestation (38% male from 0.2 to 0.79 gestation). Captivity also induced a strongly male-biased (67% male) BSR for conceptions after arrival in captivity. The results indicate the action of at least two sex-allocation mechanisms operating in sequence, confirm the important role of sex-differential embryo death around implantation and of stress in sex allocation, and lend support to suggestions that sex-differential glucose metabolism by the preimplantation embryo likely plays a role in facultative BSR adjustment.
New Zealand Journal of Zoology, 2009
We compare the number of medium‐sized animals (between rat and dog‐size) killed on repeated count... more We compare the number of medium‐sized animals (between rat and dog‐size) killed on repeated counts along the same 1660 km of North Island highways in 1984, 1994 and 2005 with other counts going back to 1949. Elevenmammal and 14 bird species were recorded, but Australian possums (Trichosurus vulpecula), hedgehogs (Erinaceus europaeus) and rabbits (Oryctolagus cuniculus) predominated, and pukekos (Porphyrio porphyrio),
Journal of Wildlife Management, 2008
... released 1 E-mail: [email protected] 2 Present address: Centre for Biodiversity and R... more ... released 1 E-mail: [email protected] 2 Present address: Centre for Biodiversity and Restoration Ecology, School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand ...
Journal of Animal Physiology and Animal Nutrition, 2011
Hydrobiologia, 1995
Breakdown of leaves from three native riparian tree species, and their colonisation by shredding ... more Breakdown of leaves from three native riparian tree species, and their colonisation by shredding and collecting insect larvae, were investigated in three streams on Banks Peninsula, New Zealand . Leaves were introduced in baskets at the time of leaf fall . Breakdown rates of leaves were faster than previously recorded in New Zealand streams and were comparable to those of many northern hemisphere deciduous species . Shredder and total detritivore densities and biomass in leaf baskets were also greater than previously found in New Zealand streams . Peaks of shredder biomass on red beech and mahoe leaves were found when only about 20% of leaf biomass remained. No shredder peak was recorded on fuchsia leaves, and no collector peaks occurred in any of the streams . Relative shredder and collector biomass (per g DW leaf) in leaf baskets did not exceed or was smaller than in leaf litter accumulations of mixed origin and conditioning throughout the streams during leaf breakdown although absolute shredder and collector biomass (per m 2 stream bottom) was occasionally larger in baskets than in the rest of the stream. These findings support contentions that spatial and temporal relationships between detrital inputs and detritivore biomass and life histories are weak in New Zealand streams .
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Papers by Wayne Linklater