Microhabitat choice and its role in determining the distribution of the reptile tick <i>Amblyomma vikirri</i>

Duffield, G. A.; Bull, C. Michael

doi:10.1111/j.1442-9993.1996.tb00607.x

Cited by 7 publications

(3 citation statements)

References 37 publications

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“…Although pasture, shrub and forest are structurally different, suitable microhabitat for ticks may be available in each. Reptilian ticks often wait for a host in leaf litter or host refuges (Bull, 1986; Duffield & Bull, 1996; Kerr & Bull, 2006). Tuatara occupy burrows that are constructed by seabirds (Newman, 1987), which provide a moist, protected environment in which ticks can locate a new host.…”

Section: Discussionmentioning

confidence: 99%

Seasonal and spatial dynamics of ectoparasite infestation of a threatened reptile, the tuatara (Sphenodon punctatus)

Godfrey

Bull

Nelson

2008

Medical Vet Entomology

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The conservation of threatened vertebrate species and their threatened parasites requires an understanding of the factors influencing their distribution and dynamics. This is particularly important for species maintained in conservation reserves at high densities, where increased contact among hosts could lead to increased rates of parasitism. The tuatara (Sphenodon punctatus) (Reptilia: Sphenodontia) is a threatened reptile that persists at high densities in forests (approximately 2700 tuatara/ha) and lower densities in pastures and shrubland (< 200 tuatara/ha) on Stephens Island, New Zealand. We investigated the lifecycles and seasonal dynamics of infestation of two ectoparasites (the tuatara tick, Amblyomma sphenodonti, and trombiculid mites, Neotrombicula sp.) in a mark-recapture study in three forest study plots from November 2004 to March 2007, and compared infestation levels among habitat types in March 2006. Tick loads were lowest over summer and peaked from late autumn (May) until early spring (September). Mating and engorgement of female ticks was highest over spring, and larval tick loads subsequently increased in early autumn (March). Nymphal tick loads increased in September, and adult tick loads increased in May. Our findings suggest the tuatara tick has a 2- or 3-year lifecycle. Mite loads were highest over summer and autumn, and peaked in March. Prevalences (proportion of hosts infected) and densities (estimated number of parasites per hectare) of ticks were similar among habitats, but tick loads (parasites per host) were higher in pastures than in forests and shrub. The prevalence and density of mites was higher in forests than in pasture or shrub, but mite loads were similar among habitats. We suggest that a higher density of tuatara in forests may reduce the ectoparasite loads of individuals through a dilution effect. Understanding host-parasite dynamics will help in the conservation management of both the host and its parasites.

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Section: Discussionmentioning

confidence: 99%

Seasonal and spatial dynamics of ectoparasite infestation of a threatened reptile, the tuatara (Sphenodon punctatus)

Godfrey

Bull

Nelson

2008

Medical Vet Entomology

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“…For instance, they are more exposed in some microhabitats than in others to predators (Bauwens et al . 1999) or parasites (Duffield & Bull 1996;Zippel et al . 1996).…”

Section: Introductionmentioning

confidence: 99%

Refuge sites used by the scincid lizard Tiliqua rugosa

Kerr¹,

Bull²,

Burzacott³

2008

Austral Ecology

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We examined microhabitat use by the Australian scincid lizard Tiliqua rugosa (the sleepy lizard) in chenopod shrubland. Thirty radiotagged lizards were followed during their spring period of activity (September-November 2000). Characteristics of refuges used by the lizards were compared with the perennial woody plants in 10 10 m ϫ 10 m randomly located quadrats at each of the three sites in the study area. We found that sleepy lizards used multiple refuge sites. Perennial woody bushes constituted an important habitat component for both active and inactive lizards. Use of refuge sites by the lizards was non-random. They used large bushes with foliage in contact with the ground ('dome shaped'), and they sheltered under thorny bushes more frequently than expected if choice was random. Bushes that were used repeatedly tended to be larger and were more likely to be dome-shaped. Under these large and dome-shaped bushes, daytime temperatures were lower than under smaller bushes. Refuge use was modified as the season progressed, with lizards using larger bushes and a greater proportion of dome-shaped bushes later in the season. We suggest that sleepy lizards are modifying their refuge site use as ambient temperatures increase, based on microclimatic needs, implying an ability to discriminate among bushes.

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“…However, as maintaining body-water equilibrium is key to off-host survival, desiccation, as well as predation and eventual starvation pose significant risks during free-living periods, especially if reattachment does not occur (Bull et al 1988;Oliver 1989;Needham & Teel 1991). As such, ticks are considered unlikely to travel far from sites where they detach and A. sphenodonti is thought to employ a "sit-and-wait" strategy seen in related tick species, residing in refuges frequented by tuatara (Petney et al 1983;Duffield & Bull 1996;Kerr & Bull 2006;Godfrey et al 2010aGodfrey et al , 2011b. Accordingly, laboratory microcosm and activity experiments have found that A. sphenodonti, like their hosts, are most active at night and show microhabitat preferences for moist, coarse, and shaded substrates, comparable to the inside of a tuatara burrow, thereby reducing desiccation risk and maximising reattachment opportunities (Heath 2006;Kerr & Bull 2006;Godfrey et al 2011b).…”

Section: Amblyomma Sphenodonti Was Originally Classified As Belonging To the Genusmentioning

confidence: 99%

Using conservation translocations to assess the impact of anthropogenic climate change on a cold-adapted reptile, the tuatara (Sphenodon punctatus)

Price¹

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<p>Anthropogenic climate change is progressing at a rate unprecedented in the past 65 million years and is a significant conservation concern. The associated biotic and abiotic impacts are expected to have substantial effects on global biodiversity, with some species potentially more vulnerable than others. The tuatara (Sphenodon punctatus) is a New Zealand endemic reptile and of particular interest as it is a slowly reproducing, range-restricted, cold-adapted ectotherm with temperature-dependent sex determination. Consequently, tuatara could be particularly vulnerable to rising air temperatures and conservation translocations have been key components of tuatara conservation efforts. Knowledge of how the tuatara might be affected by warmer climates will help inform where future conservation efforts are best directed, practices to avoid and which sites might be most suitable for the establishment of populations. The translocation of 176 adult tuatara in October 2012 from Stephens Island in New Zealand’s Cook Strait to four latitudinally distant North Island sites offered the opportunity to study the responses of tuatara in a range of environments. The comparatively warmer, drier climates of several sites provided surrogates for temporal climate change, enabling an assessment of how a warming climate might impact tuatara, and how they might respond. Using field observations, laboratory analysis and controlled experiments I investigated the short-term success of the translocations, the influence of translocation and climate on tuatara enteric bacterial communities and parasites, as well as how warmer climates might influence nocturnal activity, thermoregulatory opportunities and learning ability. I found several translocated populations to be progressing favourably, and found evidence that tuatara may exhibit enhanced growth at warmer, less densely-populated sites, suggesting that further translocations to lower latitude sites might be a viable conservation strategy. However, high population density at one translocation site was a concern and management recommendations were made to enable the dispersal of individuals. I detected Salmonella Saintpaul for the first time in a live tuatara, Campylobacter spp. was identified as a likely common commensal organism, and no measurable impact of translocation or climate on bacterial prevalence was observed, suggesting no substantial risk of climate warming to the susceptibility of tuatara to these bacteria. Tick populations were negatively impacted by translocation-associated factors following release but subsequently recovered at most sites and mites were not found on any translocated tuatara. Diurnal and nocturnal activities were positively influenced by air temperature, up to an upper threshold, and assessment of the site-specific thermal climates suggested that tuatara at warmer sites may benefit from increased opportunities for emergence and the attainment of preferred body temperatures throughout the year, though a higher frequency of restrictive air temperatures over summer may also reduce emergence opportunities. Experimental work showed that warmer air temperatures may enhance learning in tuatara, which could improve their ability to cope with challenging environments under climate change. However, body size was also an influential component of learning ability and further research is needed to build on these initial findings. I conclude that tuatara may experience overall benefits from further translocations to warmer sites and warming climates at currently cooler sites, which suggests that other cold-adapted reptiles with similar thermal tolerances may also see initial benefits under climate warming, though further monitoring is required to determine longer-term translocation success. Equally, while warmer air temperatures were not found to be detrimental to tuatara, they still pose a risk to population viability and further work is required on the impacts of associated abiotic factors like drought, and how populations of this long-lived species may be affected if and when climate warming exceeds the upper temperature rise of ~5°C predicted by the 2100s.</p>

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Microhabitat choice and its role in determining the distribution of the reptile tick Amblyomma vikirri

Cited by 7 publications

References 37 publications

Seasonal and spatial dynamics of ectoparasite infestation of a threatened reptile, the tuatara (Sphenodon punctatus)

Seasonal and spatial dynamics of ectoparasite infestation of a threatened reptile, the tuatara (Sphenodon punctatus)

Refuge sites used by the scincid lizard Tiliqua rugosa

Using conservation translocations to assess the impact of anthropogenic climate change on a cold-adapted reptile, the tuatara (Sphenodon punctatus)

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