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Sociality in mole rats has been suggested to have evolved as a response to the widely dispersed food resources and the limited burrowing opportunities that result from sporadic rainfall events. In the most arid regions, individual foraging efficiency is reduced and energetic constraints increase. In this study, we investigate seasonal differences in burrow architecture of the social Cryptomys hottentotus hottentotus in a mesic region. We describe burrow geometry in response to seasonal weather conditions for two seasons (wet and dry). Interactions occurred between seasons and colony size for the size of the burrow systems, but not the shape of the burrow systems. The fractal dimension values of the burrow systems did not differ between seasons. Thus, the burrow complexity was dependent upon the number of mole rats present in the social group.

Most polygynous male mammals exhibit little or no parental care or involvement raising young. Instead, they invest indirectly in their own morphological and physiological attributes which enhance their chance of reproduction. Such secondary morphological sex traits may contribute to differences in the burrow architecture of fossorial mammals, such as the Cape dune mole-rat, Bathyergus suillus. Indeed, little is known about the seasonal changes in burrow architecture or differences in burrow configuration may differ between the sexes of subterranean African mole-rats (Bathyergidae). We excavated burrow systems of male and female B. suillus during the summer and the winter to investigate whether male burrow architecture reflected putative mate-seeking behaviour. We consider burrow geometry in response to mating strategies. Male burrow systems explored the environment more efficiently than females. This is presumably because of the increase in associated energetic costs of being a large male. Males produce more mounds indicating territorial behaviour even when it is energetically costly to dispose of soil onto the surface when the soil is less friable during the summer. Overall tunnel dimensions did not differ between the sexes. It appears that a change in season does not affect the geometry of the burrow system or tunnel dimensions in a climatically buffered environment.

Little is known about how season influences burrowing activity, burrow structure or reproductive behaviour in subterranean mammals. We excavated burrow systems of male and female Georychus capensis, a solitary, subterranean rodent, in winter (wet season) and summer (dry season) to investigate whether, if any, seasonal differences were due to putative mate-seeking behaviour of males. Burrow structure differed between seasons but not between sexes. For both sexes, summer burrows were shorter and covered a smaller area, but explored the surrounding environment more efficiently than winter burrows. Summer burrows had fewer mounds, which indicated that less expansion of the burrow systems occurred during this season. We discuss these differences in exploration and the use of the environment between seasons in terms of mating strategies of G.capensis and observed levels of sexual dimorphism in our populations. This study supports recent ideas regarding sexual selection relating to exaggerated traits in females, which affect a female's ability to acquire reproductive resources that often appear similar to that selected for by males.

Little is known about how season influences burrowing activity, burrow structureor reproductive behaviour in subterranean mammals. We excavated burrowsystems of male and female Georychus capensis, a solitary, subterranean rodent, inwinter (wet season) and summer (dry season) to investigate whether, if any,seasonal differences were due to putative mate-seeking behaviour of males.Burrow structure differed between seasons but not between sexes. For both sexes,summer burrows were shorter and covered a smaller area, but explored the surroundingenvironment more efficiently than winter burrows. Summer burrowshad fewer mounds, which indicated that less expansion of the burrow systemsoccurred during this season. We discuss these differences in exploration and theuse of the environment between seasons in terms of mating strategies of G. capensisand observed levels of sexual dimorphism in our populations. This studysupports recent ideas regarding sexual selection relating to exaggerated traits infemales, which affect a female’s ability to acquire reproductive resources that oftenappear similar to that selected for by males.

Organisms respond to cyclical environmental conditions by entraining their endogenous biological rhythms. Suchphysiological responses are expected to be substantial for species inhabiting arid environments which incur large variationsin daily and seasonal ambient temperature (Ta). We measured core body temperature (Tb) daily rhythms of Cape groundsquirrels Xerus inauris inhabiting an area of Kalahari grassland for six months from the Austral winter through to thesummer. Squirrels inhabited two different areas: an exposed flood plain and a nearby wooded, shady area, and occurred indifferent social group sizes, defined by the number of individuals that shared a sleeping burrow. Of a suite of environmentalvariables measured, maximal daily Ta provided the greatest explanatory power for mean Tb whereas sunrise had greatestpower for Tb acrophase. There were significant changes in mean Tb and Tb acrophase over time with mean Tb increasingand Tb acrophase becoming earlier as the season progressed. Squirrels also emerged from their burrows earlier andreturned to them later over the measurement period. Greater increases in Tb, sometimes in excess of 5uC, were noted duringthe first hour post emergence, after which Tb remained relatively constant. This is consistent with observations that squirrelsentered their burrows during the day to ‘offload’ heat. In addition, greater Tb amplitude values were noted in individualsinhabiting the flood plain compared with the woodland suggesting that squirrels dealt with increased environmentalvariability by attempting to reduce their Ta-Tb gradient. Finally, there were significant effects of age and group size on Tbwith a lower and less variable Tb in younger individuals and those from larger group sizes. These data indicate that Capeground squirrels have a labile Tb which is sensitive to a number of abiotic and biotic factors and which enables them to beactive in a harsh and variable environment.

Most polygynous male mammals exhibit little or no parental care or involvement raising young. Instead, they invest indirectly in their own morphological and physiological attributes which enhance their chance of reproduction. Such secondary morphological sex traits may contribute to differences in the burrow architecture of fossorial mammals, such as the Cape dune mole-rat, Bathyergus suillus. Indeed, little is known about the seasonal changes in burrow architecture or differences in burrow configuration may differ between the sexes of subterranean African mole-rats (Bathyergidae). We excavated burrow systems of male and female B. suillus during the summer and the winter to investigate whether male burrow architecture reflected putative mate-seeking behaviour. We consider burrow geometry in response to mating strategies. Male burrow systems explored the environment more efficiently than females. This is presumably because of the increase in associated energetic costs of being a large male. Males produce more mounds indicating territorial behaviour even when it is energetically costly to dispose of soil onto the surface when the soil is less friable during the summer. Overall tunnel dimensions did not differ between the sexes. It appears that a change in season does not affect the geometry of the burrow system or tunnel dimensions in a climatically buffered environment.

The optimal dose of medetomidine-ketamine-buprenorphine was determined in 25 Cape ground squirrels (Xerus inauris) undergoing surgical implantation of a temperature logger into the abdominal cavity. At the end of anaesthesia, the squirrels were given atipamezole intramuscularly to reverse the effects of medetomidine. The mean dose of medetomidine was 67.6±9.2 µg/kg, ketamine 13.6±1.9 mg/kg and buprenorphine 0.5±0.06 µg/kg. Induction time was 3.1 ± 1.4 min. This produced surgical anaesthesia for 21± 4.2 min. Atipamezole 232±92 µg/kg produced a rapid recovery. Squirrels were sternally recumbent in 3.5 ± 2.2 min.

Many lizard species will shed their tail as a defensive response (e.g., to escape a putative predator or aggressive conspecific). This caudal autotomy incurs a number of costs as a result of loss of the tail itself, loss of resources (i.e., stored in the tail or due to the cost of regeneration), and altered behavior. Few studies have examined the metabolic costs of caudal autotomy. A previous study demonstrated that geckos can move faster after tail loss as a result of reduced weight or friction with the substrate; however, there are no data for the effects of caudal autotomy on locomotory energetics. We examined the effect of tail loss on locomotory costs in the Cape dwarf gecko Lygodactylus capensis (∼0.9 g) using a novel method for collecting data on small lizards, a method previously used for arthropods. We measured CO 2 production during 5-10 min of exhaustive exercise (in response to stimulus) and during a 45-min recovery period. During exercise, we measured speed (for each meter moved) as well as total distance traveled. Contrary to our expectations, tailless geckos overall expended less effort in escape running, moving both slower and for a shorter distance, compared with when they were intact. Tailless geckos also exhibited lower excess CO2 production (CO2 production in excess of normal resting metabolic rate) during exercising. This may be due to reduced metabolically active tissue (tails represent 8.7% of their initial body mass). An alternative suggestion is that a change in energy substrate use may take place after tail loss. This is an intriguing finding that warrants future biochemical investigation before we can predict the relative costs of tail loss that lizards might experience under natural conditions.

While females are traditionally thought to invest more time and energy into parentalcare than males, males often invest more resources into searching and displaying formates, obtaining mates and in male–male conflict. Solitary subterranean mammalsperform these activities in a particularly challenging niche, necessitating energeticallyexpensive burrowing to both search for mates and forage for food. This restrictionpresumably affects males more than females as the former are thought to dig longertunnels that cover greater distances to search for females. We excavated burrowsystems of male and female Cape dune mole rats Bathyergus suillus the, largest trulysubterranean mammal, to investigate whether male burrows differ from those offemales in ways that reflectmate searching bymales. We consider burrow architecture(length, internal dimensions, fractal dimension of tunnel systems, number of nestingchambers and mole mounds on the surface) in relation to mating strategy. Malesexcavated significantly longer burrow systems with higher fractal dimensions andlarger burrow areas than females.Male burrow systems were also significantly fartherfrom one another than females were from other females’ burrow systems. However,no sex differences were evident in tunnel cross-sectional area, mass of soil excavatedper mound, number of mounds produced per unit burrow length or mass of soilexcavated per burrow system. Hence, while males may use their habitat differentlyfrom females, they do not appear to differ in the dimensions of the tunnels they create.Thus, exploration and use of the habitat differs between the sexes, which may be aconsequence of sex differences in mating behaviour and greater demands for food.