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Is communal burrowing or burrow sharing a benefit of group living in the lesser cavy Microcavia australis?

100%

Taraborelli P.

Acta Theriologica

2009

tom 54

nr 3

249-258

Burrow systems play an important role in the life of rodents in arid environments. The objectives of this study were to examine the hypothesis that group living is beneficial to the semifossorial rodent, and determine whether Microcavia australis (Geoffroy and d’Orbigny, 1833) burrows communally and/or shares burrow systems. I related the structure of burrow systems to the number of cavies inhabiting them, in two habitats with different soil hardness and different plant cover (El Leoncito and Ñacuñán). El Leoncito has a harsh climate, with lower plant density and softer soil than Ñacñuán. A total of 18 burrow systems were characterized at Ñacuñán, and 12 at El Leoncito. Social groups at El Leoncito have a higher number of individuals than at Ñacuñán, but the structure of burrow systems in softer soil is narrower (small area size), with fewer holes, less slope and depth of galleries, and with no relationship between the number of holes and burrow area. Therefore, considering the development of the burrow system as an indicator of the cost of burrowing, I conclude that communal burrowing to reduce the energetic cost of burrowing per capita is not the primary cause of cavy sociality. M. australis were not active diggers, because digging behaviour was rarely recorded at either site. Burrow systems of cavies persisted over the years of study, occupied by the same cavies and new offspring, and digging new burrow systems and tunnels was a relatively rare event at both sites. Under the burrow-sharing hypothesis, sociality could prevail in M. australis that regularly dig to build and maintain a burrow system which they use for a long time.

Different factors that modify anti-predator behaviour in guanacos (Lama guanicoe)

33%

Taraborelli P., Ovejero R., Mosca Torres M. E., Schroeder N. M., Moreno P., Gregorio P., Macotti E., Morozzi A., Carmanchahi P.

Acta Theriologica

2014

tom 59

nr 4

Animals optimize the trade-off between the cost of not fleeing and the benefits of staying because the factors that influence flight decisions and the disturbance level of a particular stimulus can vary both spatially and temporally. Different factors (human impact and habitat characteristics) likely to modify anti-predator behaviour in different types of guanaco social groups were analysed. We found that group size was conditioned by high poaching, vehicle traffic, predation risk and vegetation density. Solitary adult males showed shorter alert and flight initiation distances than bachelor and mixed groups. Alert distance was greater during the summer season, and assessment times were shorter when young were present in the groups. In high-predation-risk environments, guanacos detected threats at greater distances and flight initiation distance was longer. Alert distances were shorter on steeper sloped hills and assessment times were shorter in areas with irregular topography than on flat sites. In high traffic areas, flight initiation distance was longer and assessment times were shorter. And in areas with low poaching intensity, assessment times were greater than in those with high poaching levels. Therefore, guanacos may be able to evaluate a true threat. Social group and anti-predator responses were conditioned by habitat characteristics and human impact. We consider that plasticity of responses could be key to the survival of guanacos.

Ograniczanie wyników

2 Acta Theriologica

2 Taraborelli P.

1 Carmanchahi P.

1 Gregorio P.

1 Macotti E.

1 Moreno P.

1 Morozzi A.

1 Mosca Torres M. E.

1 Ovejero R.

1 Schroeder N. M.

1 2014

1 2009

Wyniki wyszukiwania

Is communal burrowing or burrow sharing a benefit of group living in the lesser cavy Microcavia australis?

Different factors that modify anti-predator behaviour in guanacos (Lama guanicoe)