Refuge characteristics and preferences of Psammobates oculifer in semi-arid savanna

in Amphibia-Reptilia
Restricted Access
Get Access to Full Text
Rent on DeepDyve

Have an Access Token?



Enter your access token to activate and access content online.

Please login and go to your personal user account to enter your access token.



Help

Have Institutional Access?



Access content through your institution. Any other coaching guidance?



Connect

The availability of suitable refuges to buffer temperature extremes may be a critical determinant in the distribution of arid-zone ectotherms. We studied refuge selection of Kalahari tent tortoises over five seasons in two vegetation types to assess how seasonal climate change, vegetation type, and the size difference between sexes influence refuge selection. Plant refuges accounted for 78% and mammal burrows for 22% of refuges used. Burrow use did not differ between vegetation types or sexes but its use increased exponentially with maximum temperature, indicating that mammal burrows may be an essential resource to protect small-bodied tortoises against summer heat. Kalahari tent tortoises preferred grass refuges to other growth forms, whether shrubs or grasses were dominant in the habitat. Tall grass was selected in excess of availability, by males and females in both vegetation types, probably because it was denser than short grass and provided better protection against heat and predators. The increased use of short grass refuges in colder months may be linked to thermal needs because this growth form allowed P. oculifer to bask in filtered sunlight whilst being in cover. Females made greater use than males did of short grass refuges, perhaps because their larger size necessitated longer exposure to sunlight. Body size differences also explain why males required wider and denser refuges than females did to protect them against environmental hazards. Our results underscore the complexities of refuge selection by an arid-zone ectotherm and the role it may play in their distribution.

Refuge characteristics and preferences of Psammobates oculifer in semi-arid savanna

in Amphibia-Reptilia

Sections

References

AuffenbergW.WeaverW.G.Jr. (1969): Gopherus berlandieri in southeastern Texas. Bull. Fla. Stat. Mus. 13: 141-203.

BaileyB.J.R. (1980): Large sample simultaneous confidence-intervals for the multinomial probabilities based on transformations of the cell frequencies. Technometrics 22: 583-589.

BeckD.D.JenningsR.D. (2003): Habitat use by gila monsters: the importance of shelters. Herpetol. Monogr. 17: 111-129.

Blouin-DemersG.WeatherheadP.J. (2002): Habitat-specific behavioural thermoregulation by black rat snakes (Elaphe obsoleta obsoleta). Oikos 97: 59-68.

BoycottR.C.BourquinO. (2000): The Southern African Tortoise Book. HiltonSouth Africa.

BoyerD.R. (1965): Ecology of the basking habit in turtles. Ecology 46: 99-118.

BranchW.R. (1998): Field Guide to Snakes and Other Reptiles of Southern Africa3rd Edition. StruikCape Town.

CherryS. (1996): A comparison of confidence interval methods for habitat use-availability studies. J. Wildl. Manage. 60: 653-658.

Cloudsley-ThompsonJ.L. (1999): The Diversity of Amphibians and Reptiles: an Introduction. Springer-VerlagBerlin.

CongdonJ.D. (1989): Proximate and evolutionary constraints on energy relations of reptiles. Physiol. Zool. 62: 356-373.

DouglasR.M.RallM. (2006): Seasonal shelter selection by leopard tortoises (Geochelone pardalis) in the Franklin Nature Reserve, Free State, South Africa. Chelonian Conserv. Biol. 5: 121-129.

DownesS.ShineR. (1998): Heat, safety or solitude? Using habitat selection experiments to identify a lizard’s priorities. Anim. Behav. 55: 1387-1396.

DudaJ.J.KrzysikA.J.MelocheJ.M. (2002): Spatial organization of desert tortoises and their burrows at a landscape scale. Chelonian Conserv. Biol. 4: 387-397.

EbrahimiM.FennerA.L.BullC.M. (2012): Lizard behaviour suggests a new design for artificial burrows. Wildl. Res. 39: 295-300.

GeffenE.MendelssohnH. (1989): Activity patterns and thermoregulatory behavior of the Egyptian tortoise, Testudo kleinmanni, in Israel. J. Herpetol. 23: 404-409.

GermishuizenG.MeyerN.L. (2003): Plants of Southern Africa: an annotated checklist. Strelitzia 14. National Botanical Institute Pretoria.

GrantB.W.DunhamA.E. (1988): Thermally imposed time constraints on the activity of the desert lizard Sceloporus merriami. Ecology 69: 167-176.

GriggG.C.DraneC.R.CourticeG.P. (1979): Time constants of heating and cooling in the eastern water dragon, Physignathus lesueruii and some generalizations about heating and cooling in reptiles. J. Therm. Biol. 4: 95-103.

GrilletP.CheylanM.ThirionJ.-M.DoréF.BonnetX.DaugeC.CholletS.MarchandM.A. (2010): Rabbit burrows or artificial refuges are a critical habitat component for the threatened lizard, Timon lepidus (Sauria, Lacertidae). Biodivers. Conserv. 19: 2039-2051.

HenenB.T. (1997): Seasonal and annual energy budgets of female desert tortoises (Gopherus agassizii). Ecology 78: 283-296.

HillR.A. (1999): Size-dependent tortoise predation by baboons at De Hoop Nature Reserve, South Africa. S. Afr. J. Sci. 95: 123.

HofmeyrM.D.BoycottR.C.BaardE.H.W. (in press): Family: Testudinidae. In: Atlas and Red List of the Reptiles of South Africa Lesotho and Swaziland. BatesM.F.BranchW.R.BauerA.M.BurgerM.MaraisJ.AlexanderG.J.de VilliersM.S. Eds South African Biodiversity InstitutePretoria.

HolmS. (1979): A simple sequentially rejective multiple test procedure. Scand. J. Statist. 6: 65-70.

HueyR.B. (1991): Physiological consequences of habitat selection. Am. Nat. 137: S91-S115.

HueyR.B.BennettA.F. (1990): Physiological adjustments to fluctuating thermal environments: an ecological and evolutionary perspective. In: Stress Proteins in Biology and Medicine p.  37-59. MormiotoR.I.TissièresA.GeorgopoulosC. Eds Cold Spring Harbor Laboratory PressNorth America.

JoshuaQ.I.HofmeyrM.D.HenenB.T.WeitzF.M. (2005): Seasonal changes in the vegetation of island and mainland habitats of angulate tortoises in the Western Cape, South Africa. S. Afr. J. Sci. 101: 439-445.

KeswickT. (2012): Ecology and morphology of the Kalahari tent tortoise Psammobates oculifer in a semi-arid environment. Ph.D. thesis University of the Western Cape Belville South Africa.

KeswickT.HenenB.T.HofmeyrM.D. (2006): Sexual disparity in activity patterns and time budgets of angulate tortoises (Chersina angulata) on Dassen Island, South Africa. Afr. Zool. 41: 224-233.

KinlawA. (1999): A review of burrowing by semi-fossorial vertebrates in arid environments. J. Arid Environ. 41: 127-145.

LagardeF.LouziziT.SlimaniT.El MoudenH.Ben KaddourK.MoulheratS.BonnetX. (2012): Bushes protect tortoises from lethal overheating in arid areas of Morocco. Environ. Conserv. 39: 172-182.

LeistnerO.A. (1967): The plant ecology of the southern Kalahari. Mem. Bot. Surv. S. Afr. 38: 1-140.

NagyK.A.MedicaP.A. (1986): Physiological ecology of desert tortoises in southern Nevada. Herpetologica 42: 73-92.

PlummerM.V. (2003): Activity and thermal ecology of the box turtle, Terrapene ornata, at its southwestern range limit in Arizona. Chelonian Conserv. Biol. 4: 569-577.

PoughF.H. (1980): The advantages of ectothermy for tetrapods. Am. Nat. 115: 92-112.

PressW.H.FlanneryB.P.TeukolskyS.A.VetterlingW.T. (1986): Numerical Recipes. Cambridge University PressCambridge.

RutherfordM.C.MucinaL.LotterM.C.BredenkampG.J.SmitJ.H.L.Scott-ShawC.R.HoareD.B.GoodmanP.S.BezuidenhoutH.ScottL.EllisF.PowrieL.W.SiebertF.MostertT.H.HenningB.J.VentnerC.E.CampK.G.T.SiebertS.J.MatthewsW.S.BurrowsJ.E.DobsonL.van RooyenN.SchmidtE.WinterP.J.D.du PreezP.J.WardR.A.WilliamsonS.HurterP.J.H. (2006): Savanna Biome. In: The Vegetation of South Africa Lesotho and Swaziland p.  440-529. MucinaL.RutherfordM.C. Eds South African National Biodiversity InstitutePretoria.

SeebacherF.FranklinC.E. (2005): Physiological mechanisms of thermoregulation in reptiles: a review. J. Comp. Physiol. B Biochem. Syst. Environ. Physiol. 175: 533-541.

SkinnerJ.D.ChimimbaC.T. (2005): The Mammals of the Southern African Subregion. Cambridge University PressCambridge.

SpencerR.ThompsonM.B.HumeI.D. (1998): The diet and digestive energetics of an Australian short-necked turtle, Emydura macquarii. Comp. Biochem. Physiol. Part A Mol. Integr. Physiol. 121: 341-349.

StevensonR.D. (1985a): The relative importance of behavioral and physiological adjustments controlling body temperature in terrestrial ectotherms. Am. Nat. 126: 362-386.

StevensonR.D. (1985b): Body size and limits to the daily range of body temperature in terrestrial ectotherms. Am. Nat. 125: 102-117.

StoreyK.B. (2006): Reptile freeze tolerance: metabolism and gene expression. Cryobiology 52: 1-16.

van OudtshoornF. (2004): Guide to Grasses of Southern Africa2nd Edition. Briza PublicationsPretoria.

ZarJ.H. (2001): Biostatistical Analysis4th Edition. Prentice HallUpper Saddle River, New Jersey.

ZimmermanL.C.O’ConnorM.P.BulovaS.J.SpotilaJ.R.KempS.J.SaliceC.J. (1994): Thermal ecology of desert tortoises in the eastern Mojave Desert: seasonal patterns of operative and body temperatures, and microhabitat utilization. Herpetol. Monogr. 8: 45-49.

Figures

  • View in gallery

    (a) Monthly rainfall at the study site and at Kimberley airport, ca. 5 km from the study site, and the long-term rainfall average (± SD; 46 years, 1960-2005) at Kimberley airport. (b) Mean monthly maxima and minima temperatures (± SD) for the study period at Kimberley airport.

  • View in gallery

    Mean (± SD) monthly refuge widths (a) and heights (b). No data were collected in June 2006 and data of the first and last days of November were added to October and December, respectively.

  • View in gallery

    Seasonal use of refuge types by Psammobates oculifer in combined sites. Refuge types include mammal burrows (black bars), short grass (hatched bars), tall grass (grey bars), short shrubs (white bars) and remaining refuge types (horizontal bars) which had small occurrences (unknown grass, herbs, tall shrubs and trees).

Index Card

Content Metrics

Content Metrics

All Time Past Year Past 30 Days
Abstract Views 15 15 8
Full Text Views 8 8 8
PDF Downloads 3 3 3
EPUB Downloads 0 0 0