Credit
We at TERN acknowledge the Traditional Owners and Custodians throughout Australia, New Zealand and all nations. We honour their profound connections to land, water, biodiversity and culture and pay our respects to their Elders past, present and emerging.
We gratefully acknowledge the farmers who gave us permission to work on their farms.
Purpose
Native biodiversity in Australian agricultural landscapes continues to decline in response to a range of threatening processes. Woody perennial farming systems are being established across southern Australia as land managers strive to achieve more sustainable and profitable farming practices. Woody perennial farming systems can improve the persistence of biota either directly, for example, by providing additional food resources; or indirectly by ameliorating risk factors, such as altered hydrological processes, that are threatening biota. The focus of the program is on the food, shelter and breeding resources that perennial farming systems can provide for native biota and thus potentially contribute to the persistence of a range of native species in agricultural landscapes. Native biodiversity in Australian agricultural landscapes continues to decline in response to a range of threatening processes. Woody perennial farming systems are being established across southern Australia as land managers strive to achieve more sustainable and profitable farming practices. Woody perennial farming systems can improve the persistence of biota either directly, for example, by providing additional food resources; or indirectly by ameliorating risk factors, such as altered hydrological processes, that are threatening biota. The focus of the program is on the food, shelter and breeding resources that perennial farming systems can provide for native biota and thus potentially contribute to the persistence of a range of native species in agricultural landscapes. There were four studies: (i) Study 1 was a review of the resource requirements of all terrestrial vertebrate species found in the temperate agricultural landscapes of South Australia and Western Australia, (ii) Study 2 studied the potential of planted saltbush (Atriplex nummularia) to support avian biodiversity in the Murray Mallee of South Australia, (iii) Study 3 explored the use of native perennial (saltbush) plantations Atriplex numularia numularia by the sleepy lizard (Tiliqua rugosa) an endemic Australian species common in the South Australian Murray Mallee region (SAMM), and (iv) Study 4 assessed the body condition and haematology of the sleepy lizard in grazed rangelands (native vegetation relatively intact) and severely modified cropping landscapes (remnants of native vegetation surrounded by cereal crops) to determine lizard health and make inferences about the vulnerability of habitats under extreme of habitat modification and discuss implications for the species persistence and farming systems management. This dataset is for Study 4.
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Data Creation
Sampling design :
Two sampling designs were used to collect data on physiological health. Design 1 (Baseline vs Severe) investigated differences in the health of wild lizards using a single treatment (fixed, 2 levels: baseline habitat alteration, n = 30; severe habitat alteration, n = 30) and one covariate for body condition (2 measures: residual condition index, ectoparasite load where n = 30 for each. Design 2 (Severe only) examined the influence of habitat complexity on lizard health in the cropland landscapes using differences in two factors: (1) habitat type (fixed, 3 levels: remnant mallee woodland as small disconnected liner strips or patches with reduced habitat complexity, n = 27; revegetated saltbush, n = 28; crop/rested fields, n = 23) and (2) structural connectivity (fixed, 4 levels: low - < 63% connectedness, n = 24; medium 63-88% connectedness, n = 25; high - > 88% but not connected, n= 19; connected to mallee woodland, n = 10). Both factors were nested within three replicated sites (LS1, LS2, LS3). All blood samples were identified by age but not by sex because of unreliable sex determination using eversion of hemipenes. To assess the effect of brumation on haematological data in the Severe sites, we recorded data on the cumulative days since the first day of sampling (CUMDAYS). Ideally, repeated blood samples from the same individuals throughout the study was the preferred approach but insufficient recaptures prevented this.
Animal Survey:
Lizards were surveyed by employing a single reptile visual encounter survey using a randomised line transect method in all saltbush plantings and small remnants. Teams of two observers systematically searched neighbouring rows of monocultures of saltbush (approximately 8-10m apart)and 10m wide strip between observers in remnants at a consistent slow pace ensuring that both sides of individual saltbushes rows and 10m-wide path in the remnant were surveyed thoroughly for lizards. Multiple sampling occurred at the Baseline site and once in woodland remnants and revegetated saltbush within the severe sites over a 5-day period for 5 weeks between November and December 2010 and in February 2011 when the ground temperature was < 28 degrees C and ideally until no new captures were recorded. At the Baseline site, blood smears were collected as part of an on-going 30 year population study via toe-clipping and prepared using immediate duplicate blood smears.At the Severe sites, immediately after capture, animals were microchipped and blood taken from the caudal tail vein. Duplicate blood smears were also prepared and later stained with Wright-Giesma (Sigma-Aldrich®)). The new method of blood collection in the Severe sites followed the conditions outlined in the CSIRO Human Nutrition Animal Ethics Committee 2.0 Permit (75606/11) and the Government of South Australia Scientific Research Permit (Q258201). Captures were grouped into two categories: juveniles (SVL<200 mm) and sub-adults/adults (>=200 mm). Site capture density was estimated at 3.9 individuals per ha.
Haematological Processing:
Heparinised blood from the Severe sites was transferred to a capillary tube and the percentage of the blood that was composed of red blood cells or packed cell volume (PCV) was determined using a microcentrifuge (n=85). PCV was not determined for Baseline animals. Estimated total White Blood Cells counts, differentials ratio were enumerated using Carl Zeiss Axio® Imager 2 microscopy. The estimate count method was used where the total number of heterophils was estimated by counting the number of heterophils present in each of five fields using the 40X objective of the microscope in an area of the blood smear where the red cells first became overlapping. The number of cells per field was then averaged and the average was multiplied by 2,000 to give an estimated number of cells per microlitre. Differential counts were determined using a a modified periodic Schiff procedure by counting 100 white blood cells under 100 X magnification and recording the percentage of heterophils, lymphocytes, monocytes, and other granulocytes. The fraction of heterophils was then divided into the estimated total heterophil count to give the total white blood cell count and this was used to calculate the total monocyte, lymphocyte and other granulocyte total counts. The other granulocyte count included cells that matched the description of basophils seen in other reptile species, another cell type that contained clear round vacuoles that appeared to have degranulated, and large round cells with fine basophilic granules. The percentage of polychromatophilic red blood cells was determined by counting the number of polychromatophilic red blood cells per 200 red blood cells.
Body Size :
Body size was assessed by unity of linear body size index residual condition index (LBSIRCI). LBSIRCI was calculated from the residuals of a ranged major axis (RMA) regression between log-transformed body mass and log-transformed body length. It meets the assumptions of linearity (r = 0.73) and independence (Green 2001). Lizards were harnessed and weighed using a hand-held Pesola scale to the nearest 0.1g. Snout-vent length was measured with a ruler to the nearest 1mm.
Ectoparasite Load :
The presence or absence of ticks for each individual was recorded by searching all surface areas of a lizardÂs body. Both species of ticks are highly visible. Tick load was measured as the number of ticks per individual. The ecoparasitic ticks Aponomma hydrosauri and Amblyomma libatum are commonly found on this species in the study region.
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