Can shrub cover increase predation risk for a desert rodent?

1996 ◽  
Vol 74 (1) ◽  
pp. 157-163 ◽  
Author(s):  
Robert L. Schooley ◽  
Peter B. Sharpe ◽  
Beatrice Van Horne
Keyword(s):  
Predation Risk ◽  
Activity Patterns ◽  
Ground Squirrels ◽  
Shrub Cover ◽  
Vegetative Cover ◽  
Predator Detection ◽  
Desert Rodents ◽  
Spermophilus Townsendii ◽  
Ceratoides Lanata ◽  
One Year

Previous research indicates that predation risk may influence activity patterns, habitat partitioning, and community structure of nocturnal desert rodents. Shrub microhabitat is typically considered safer than open microhabitat for these small mammals. We investigated predation risk for Townsend's ground squirrels (Spermophilus townsendii), which are diurnal desert rodents that detect predators visually and use burrows for refuge. Our results suggested that shrub cover may increase risk for these squirrels by decreasing their ability to escape from predators. Our field experiment indicated that running speeds of juvenile squirrels were lower in shrub (Ceratoides lanata) habitat than in open areas. Shrub cover was also associated with shorter predator-detection distances (mammalian and avian) and fewer refuges (burrow entrances per hectare) than in open areas in one year but not in another. Our study demonstrated that the visual and locomotive obstruction of vegetative cover may increase predation risk for diurnal desert rodents and that elements of habitat-dependent risk may be temporally dynamic.

scholarly journals Day and night in the subterranean: measuring daily activity patterns of subterranean rodents (Ctenomys aff. knighti) using bio-logging

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Milene G Jannetti ◽  
C Loren Buck ◽  
Veronica S Valentinuzzi ◽  
Gisele A Oda
Keyword(s):  
Daily Activity ◽  
Activity Patterns ◽  
Extreme Environments ◽  
Total Duration ◽  
Time Of Day ◽  
Constant Darkness ◽  
Subterranean Rodents ◽  
Monte Desert ◽  
Direct Observations ◽  
Desert Rodents

Abstract While most studies of the impacts of climate change have investigated shifts in the spatial distribution of organisms, temporal shifts in the time of activity is another important adjustment made by animals in a changing world. Due to the importance of light and temperature cycles in shaping activity patterns, studies of activity patterns of organisms that inhabit extreme environments with respect to the 24-hour cyclicity of Earth have the potential to provide important insights into the interrelationships among abiotic variables, behaviour and physiology. Our previous laboratory studies with Argentinean tuco-tucos from the Monte desert (Ctenomys aff. knighti) show that these subterranean rodents display circadian activity/rest rhythms that can be synchronized by artificial light/dark cycles. Direct observations indicate that tuco-tucos emerge mainly for foraging and for removal of soil from their burrows. Here we used bio-logging devices for individual, long-term recording of daily activity/rest (accelerometry) and time on surface (light-loggers) of six tuco-tucos maintained in outdoor semi-natural enclosures. Environmental variables were measured simultaneously. Activity bouts were detected both during day and night but 77% of the highest values happened during the daytime and 47% of them coincided with time on surface. Statistical analyses indicate time of day and temperature as the main environmental factors modulating time on surface. In this context, the total duration that these subterranean animals spent on surface was high during the winter, averaging 3 h per day and time on surface occurred when underground temperature was lowest. Finally, transport of these animals to the indoor laboratory and subsequent assessment of their activity rhythms under constant darkness revealed a switch in the timing of activity. Plasticity of activity timing is not uncommon among desert rodents and may be adaptive in changing environments, such as the desert where this species lives.

Predator detection and dilution as benefits of associations between yellow mongooses and Cape ground squirrels

2013 ◽  
Vol 67 (7) ◽  
pp. 1187-1194 ◽  
Author(s):  
Sarah A. Makenbach ◽  
Jane M. Waterman ◽  
James D. Roth
Keyword(s):  
Ground Squirrels ◽  
Predator Detection

Remote monitoring of the behaviour and activity of captive southern hairy-nosed wombats (Lasiorhinus latifrons)

2009 ◽  
Vol 31 (2) ◽  
pp. 123 ◽  
Author(s):  
Lindsay A. Hogan ◽  
Clive J. C. Phillips ◽  
Allan Lisle ◽  
Alan B. Horsup ◽  
Tina Janssen ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Video Surveillance ◽  
Remote Monitoring ◽  
Activity Patterns ◽  
Behavioural Ecology ◽  
Radio Transmitter ◽  
Rest Periods ◽  
In The Wild ◽  
Radio Transmitters ◽  
One Year

The nocturnal nature of wombats makes it difficult to learn about their behavioural ecology and activity rhythms in the wild. A facility was established at Rockhampton Zoo to house 12 adult southern hairy-nosed wombats in order to monitor their behaviour by means of video surveillance and provide detailed information on their activity patterns using movement-sensitive radio-transmitters. After one year of monitoring it was established that the wombats spent, on average, as a proportion of total time 69.9% sleeping, 8.8% lying resting, 5.2% feeding, 5.2% exploring, 4.3% performing stereotyped behaviour, 2.5% sitting resting and 4.1% in other activities. Feeding, lying resting and sleeping varied with season by ~5%. Temporal patterns were bimodal for 8 of the 12 behaviours described, with most ‘active’ behaviours being expressed between 1800 and 2000 hours and 0200 and 0500 hours. The activity pattern was characterised by a strong circadian rhythm, with most activity occurring nocturnally. Within active periods there was an alternating rhythm of active and rest periods and activity peaks at the beginning and end of each night. Comprehensive and reliable information on the behavioural ecology, as well as captive management, of southern hairy-nosed wombats was obtained from the remote video and radio-transmitter recordings.

scholarly journals The song remains the same: Juvenile Richardson’s ground squirrels do not respond differentially to mother’s or colony member’s alarm calls

2012 ◽  
Vol 58 (5) ◽  
pp. 773-780 ◽  
Author(s):  
James F. Hare ◽  
Kurtis J. Warkentin
Keyword(s):  
Adult Female ◽  
Escape Behavior ◽  
Alarm Call ◽  
Ground Squirrels ◽  
Alarm Calls ◽  
Digital Audio ◽  
Predator Detection ◽  
Postural Responses ◽  
Limited Opportunity ◽  
Predator Model

Abstract Alarm calls are emitted by Richardson’s ground squirrels Urocitellus richardsonii in response to avian and terrestrial predators. Conspecifics detecting these calls respond with increased vigilance, promoting predator detection and evasion, but in doing so, lose time from foraging. That loss can be minimized if alarm call recipients discriminate among signalers, and weight their response accordingly. For juvenile ground squirrels, we predicted that the trade-off between foraging and vigilance could be optimized via selective response to alarm calls emitted by their own dam, and/or neighboring colony members over calls broadcast by less familiar conspecifics. Alarm calls of adult female Richardson’s ground squirrels were elicited in the field using a predator model and recorded on digital audio tape. Free-living focal juveniles were subjected to playbacks of a call of their mother, and on a separate occasion a call from either another adult female from their own colony, or an adult female from another colony. Neither immediate postural responses and escape behavior, nor the duration of vigilance manifested by juveniles differed with exposure to alarm calls of the three adult female signaler types. Thus, juveniles did not respond preferentially to alarm calls emitted by their mothers or colony members, likely reflecting the high cost of ignoring alarm signals where receivers have had limited opportunity to establish past signaler reliability.

Linking snake habitat use to nest predation risk in grassland birds: the dangers of shrub cover

Oecologia ◽  
2010 ◽  
Vol 162 (3) ◽  
pp. 803-813 ◽  
Author(s):  
Page E. Klug ◽  
Sara L. Jackrel ◽  
Kimberly A. With
Keyword(s):  
Habitat Use ◽  
Predation Risk ◽  
Nest Predation ◽  
Grassland Birds ◽  
Shrub Cover

scholarly journals Influence of Habitat on Behavior of Townsend's Ground Squirrels (Spermophilus townsendii)

1998 ◽  
Vol 79 (3) ◽  
pp. 906 ◽  
Author(s):  
Peter B. Sharpe ◽  
Beatrice van Horne
Keyword(s):  
Ground Squirrels ◽  
Spermophilus Townsendii

The effect of cover and food on space use by wintering Song Sparrows and Field Sparrows

1997 ◽  
Vol 75 (10) ◽  
pp. 1636-1641 ◽  
Author(s):  
Christopher W. Beck ◽  
Bryan D. Watts
Keyword(s):  
Predation Risk ◽  
Positive Response ◽  
Distribution Patterns ◽  
Microhabitat Use ◽  
Vegetative Cover ◽  
Song Sparrows ◽  
Trade Offs ◽  
Resource Requirements ◽  
Woody Cover ◽  
Species Specific

The distribution of birds among microhabitats may reflect species-specific resource requirements. Both food availability and predation risk have been shown to influence patterns of microhabitat use by sparrows during winter. We investigated the influence of vegetative cover and food on microhabitat use using a 2 × 2 factorial design. Both woody cover and food were manipulated at the plot level. The presence of screening cover (weed stems) was manipulated within plots. Sparrows showed a positive response to the presence of both cover and food. Within plots, sparrows selected areas with screening cover. The distribution of birds between areas with and without screening cover was influenced by the presence of woody cover and food. Conversely, the presence of screening cover reduced the influence of woody cover on the distribution of birds within patches. Song Sparrows (Melospiza melodia) and Field Sparrows (Spizella pusilla) differed in their response to treatments both within and across plots, suggesting that trade-offs between foraging and predation risk may be important in the structuring of winter sparrow assemblages. Additionally, screening cover appears to moderate predation risk and therefore to affect distribution patterns.

Habitat as a source of intrapopulational variation of ornament size in Galápagos lava lizards (Microlophus albemarlensis complex)

2008 ◽  
Vol 29 (2) ◽  
pp. 278-283 ◽  
Author(s):  
Mark Jordan ◽  
Howard Snell ◽  
Jennifer Hollis ◽  
Paul Stone
Keyword(s):  
Predation Risk ◽  
Body Mass ◽  
Predator Avoidance ◽  
Habitat Structure ◽  
Predation Pressure ◽  
Residual Body ◽  
Galápagos Islands ◽  
Vegetative Cover ◽  
High Predation ◽  
Intrapopulational Variation

Abstract Gradients in habitat structure are expected to influence the outcome of selection on traits that contribute to communicative display. Galápagos lava lizards (Microlophus albemarlensis complex) on Isla Plaza Sur in the Galápagos Islands occur across a gradient of vegetative cover. Previous work in this population has shown that traits associated with predator avoidance are magnified in habitats with low vegetative cover. This pattern suggests that predation pressure differs by habitat and thus, may act to select against the elaboration of ornamentation. We measured the size of the chin patch, an ornament known to be used in intraspecific signaling, to test this hypothesis. The area of the chin patch was dependent on both snout-vent length and residual body mass. In contrast to expectation, males had larger chin patches in the sparsely vegetated habitat suggested to have high predation risk. This result raises questions about the presumed survival cost of ornament elaboration.

scholarly journals Basking and diurnal foraging in the dasyurid marsupial Pseudantechinus macdonnellensis

2008 ◽  
Vol 56 (2) ◽  
pp. 129 ◽  
Author(s):  
Chris R. Pavey ◽  
Fritz Geiser
Keyword(s):  
Predation Risk ◽  
Arid Zone ◽  
Activity Patterns ◽  
Active Phase ◽  
Temperature Sensitive ◽  
Body Temperatures ◽  
Mammal Species ◽  
Energetic Costs ◽  
Trade Offs

Several mammal species bask to passively rewarm during arousal from torpor, a strategy that can decrease energetic costs. Nothing is known about basking behaviour in these species or the trade-offs between energetic benefits of basking and potential costs associated with changes in activity patterns and increased predation risk. We assessed basking during winter in Pseudantechinus macdonnellensis, an Australian arid-zone marsupial that belongs to a family (Dasyuridae) that is typically nocturnal. Animals were implanted with temperature-sensitive transmitters to assess body temperatures and to assist in visually locating animals active during the day. Tagged animals regularly exhibited diurnal foraging. Foraging bouts occurred throughout the day; however, most bouts were observed within 3 h of sunset. By comparison, basking occurred much more frequently in the morning. Basking and a shift towards diurnal foraging in winter is associated with a decrease in richness and abundance of predators. P. macdonnellensis appears to compensate for the occurrence of torpor during the active phase (i.e. night) in winter by changing activity patterns such that foraging commences during what is usually the rest phase. These activity patterns are not expected to occur during the remainder of the year.

Wheel-Running Activity Patterns of Five Species of Desert Rodents

2001 ◽  
Vol 32 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Gregory E. Demas ◽  
Hanan A. El-Bakry ◽  
Eric M. Mintz ◽  
Wafaa M. Zarhan ◽  
Timothy J. Bartness
Keyword(s):  
Wheel Running ◽  
Activity Patterns ◽  
Running Activity ◽  
Desert Rodents ◽  
Wheel Running Activity
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