scholarly journals Red squirrel territorial vocalizations deter intrusions by conspecific rivals

2018 ◽  
Author(s):  
Erin Siracusa ◽  
Marina Morandini ◽  
Stan Boutin ◽  
Murray M. Humphries ◽  
Ben Dantzer ◽  
...  
Keyword(s):  
Experimental Treatment ◽  
Active Role ◽  
Control Treatment ◽  
Energy Costs ◽  
Red Squirrel ◽  
Red Squirrels ◽  
Risk Of Injury ◽  
North American Red Squirrels ◽  
Territory Owner ◽  
Paired Design

AbstractIn many species, territory defense is thought to be one of the primary functions of acoustic communication. North American red squirrels are a territorial species in which ‘rattles’ have long been thought to be the principal signal communicating territory ownership. These vocalizations have been assumed to deter intruders, thus reducing energy costs and the risk of injury associated with direct aggressive interactions. However, this hypothesis has not been directly tested. Here we used a speaker occupation experiment to test whether red squirrel rattles function to deter conspecific rivals. We studied 29 male squirrels and removed each individual from his territory twice in a paired design. During the experimental treatment we simulated the owner’s presence after its removal by broadcasting the owner’s rattle from a loudspeaker at the center of the territory once every seven minutes. During the control treatment the territory was left in silence after the temporary removal of the owner. We found that the presence of a speaker replacement reduced the probability of intrusion by 34% and increased the latency to first intrusion by 7%, providing support for the hypothesis that rattles play an active role in reducing intrusion risk. However, intrusions were not completely averted by the speaker replacement, indicating that vocalizations alone are not sufficient without other cues of the territory owner.

scholarly journals Red squirrel territorial vocalizations deter intrusions by conspecific rivals

Behaviour ◽  
2017 ◽  
Vol 154 (13-15) ◽  
pp. 1259-1273 ◽  
Author(s):  
Erin Siracusa ◽  
Marina Morandini ◽  
Stan Boutin ◽  
Murray M. Humphries ◽  
Ben Dantzer ◽  
...  
Keyword(s):  
Experimental Treatment ◽  
Active Role ◽  
Control Treatment ◽  
Red Squirrel ◽  
Red Squirrels ◽  
Aggressive Interactions ◽  
Risk Of Injury ◽  
North American Red Squirrels ◽  
Territory Owner ◽  
Paired Design

Abstract In many species, territory advertisement is thought to be one of the primary functions of acoustic communication. North American red squirrels are a territorial species in which ‘rattles’ have long been thought to be the principal signal communicating territory ownership. These vocalizations have been assumed to deter intruders, thus reducing energetic costs and the risk of injury associated with direct aggressive interactions. However, this hypothesis has not been directly tested. Here we used a speaker occupation experiment to test whether red squirrel rattles function to deter conspecific rivals. We studied 29 male squirrels and removed each individual from his territory twice in a paired design. During the experimental treatment, we simulated the owner’s presence after its removal by broadcasting the owner’s rattle from a loudspeaker at the centre of the territory once every 7 min. During the control treatment, the territory was left in silence following the temporary removal of the owner. We found that the presence of a speaker replacement reduced the probability of intrusion by 34% and increased the latency to first intrusion by 7%, providing support for the hypothesis that rattles play an active role in reducing intrusion risk. However, intrusions were not completely averted by the speaker replacement, indicating that for some individuals vocalizations alone are not a sufficient deterrent without other cues of the territory owner.

scholarly journals Why do North American Red Squirrel, Tamiasciurus hudsonicus, Mothers Relocate Their Young? A Predation-based Hypothesis

2008 ◽  
Vol 122 (1) ◽  
pp. 65 ◽  
Author(s):  
Tricia Kerr ◽  
Sébastien Descamps
Keyword(s):  
North American ◽  
Tamiasciurus Hudsonicus ◽  
Red Squirrel ◽  
Red Squirrels ◽  
Efficient Strategy ◽  
North American Red Squirrels ◽  
The Impact ◽  
North American Red Squirrel

Our study reports the first observations consistent with Short-Tailed Weasel predation on juvenile North American Red Squirrels in the nest. Red Squirrel mothers are known to relocate their young to another nest after a disturbance. We suggest that this behaviour might be an efficient strategy that reduces the impact of litter depredation by weasels.

Constraints on First Reproduction in North American Red Squirrels

Oikos ◽  
1998 ◽  
Vol 81 (1) ◽  
pp. 81 ◽  
Author(s):  
C. Dustin Becker ◽  
Stan Boutin ◽  
Karl W. Larsen
Keyword(s):  
North American ◽  
Red Squirrels ◽  
First Reproduction ◽  
North American Red Squirrels

SEASONAL DAMAGE BY INSECTS AND SQUIRRELS TO FEMALE REPRODUCTIVE STRUCTURES OF BLACK SPRUCE, PICEA MARIANA (MILL.) B.S.P.

1988 ◽  
Vol 120 (12) ◽  
pp. 1113-1121 ◽  
Author(s):  
Y.H. Prévost ◽  
J.E. Laing ◽  
V.F. Haavisto
Keyword(s):  
Picea Mariana ◽  
Black Spruce ◽  
Choristoneura Fumiferana ◽  
Tamiasciurus Hudsonicus ◽  
Red Squirrel ◽  
Red Squirrels ◽  
Reproductive Structures ◽  
Cone Axis ◽  
Viable Seeds ◽  
Cone Growth

AbstractThe seasonal damage to female reproductive structures (buds, flowers, and cones) of black spruce, Picea mariana (Mill.) B.S.P., was assessed during 1983 and 1984. Nineteen insects (five Orders) and the red squirrel, Tamiasciurus hudsonicus (Erxleben), were found feeding on these reproductive structures. Collectively, these organisms damaged 88.9 and 53.5% of the cones in 1983 and 1984, respectively. In the 2 years, Lepidoptera damaged 61.8% of the cones in 1983 and 44.4% of the cones in 1984. The spruce budworm, Choristoneura fumiferana (Clem.), and the spruce coneworm, Dioryctria reniculelloides Mut. and Mun., were the most important pests. Cones damaged by Lepidoptera could be classed into three categories: (a) severe, yielding no seeds; (b) moderate, yielding 22.3 seeds per cone; and (c) light, yielding 37.5 seeds per cone. Undamaged cones yielded on average 39.9 seeds per cone. Red squirrels removed 18.8% of the cones in 1983 and none in 1984. The spruce cone axis midge, Dasineura rachiphaga Tripp, and the spruce cone maggot, Lasiomma anthracinum (Czerny), caused minor damage in both years. Feeding by spruce cone axis midge did not reduce cone growth significantly or the number of viable seeds per cone, but feeding by the spruce cone maggot did. During both years new damage by insects to the female reproductive structures of the experimental trees was not observed after mid-July. In 1983 damage by red squirrels occurred from early to late September. In 1984 damage to cones on trees treated with dimethoate was 15.6% compared with 53.5% for untreated trees, without an increase in the number of aborted cones.

North American red squirrels mitigate costs of territory defence through social plasticity

2019 ◽  
Vol 151 ◽  
pp. 29-42 ◽  
Author(s):  
Erin R. Siracusa ◽  
David R. Wilson ◽  
Emily K. Studd ◽  
Stan Boutin ◽  
Murray M. Humphries ◽  
...  
Keyword(s):  
North American ◽  
Red Squirrels ◽  
Territory Defence ◽  
Social Plasticity ◽  
North American Red Squirrels

scholarly journals Is biasing offspring sex ratio adaptive? A test of Fisher's principle across multiple generations of a wild mammal in a fluctuating environment

2018 ◽  
Vol 285 (1891) ◽  
pp. 20181251 ◽  
Author(s):  
Andrea E. Wishart ◽  
Cory T. Williams ◽  
Andrew G. McAdam ◽  
Stan Boutin ◽  
Ben Dantzer ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Tamiasciurus Hudsonicus ◽  
Red Squirrels ◽  
Offspring Sex Ratio ◽  
Offspring Sex ◽  
Adult Sex Ratio ◽  
Secondary Sex Ratio ◽  
North American Red Squirrels ◽  
Negative Frequency Dependent Selection ◽  
Fisher’S Principle

Fisher's principle explains that population sex ratio in sexually reproducing organisms is maintained at 1 : 1 owing to negative frequency-dependent selection, such that individuals of the rare sex realize greater reproductive opportunity than individuals of the more common sex until equilibrium is reached. If biasing offspring sex ratio towards the rare sex is adaptive, individuals that do so should have more grandoffspring. In a wild population of North American red squirrels ( Tamiasciurus hudsonicus ) that experiences fluctuations in resource abundance and population density, we show that overall across 26 years, the secondary sex ratio was 1 : 1; however, stretches of years during which adult sex ratio was biased did not yield offspring sex ratios biased towards the rare sex. Females that had litters biased towards the rare sex did not have more grandoffspring. Critically, the adult sex ratio was not temporally autocorrelated across years, thus the population sex ratio experienced by parents was independent of the population sex ratio experienced by their offspring at their primiparity. Expected fitness benefits of biasing offspring sex ratio may be masked or negated by fluctuating environments across years, which limit the predictive value of the current sex ratio.

scholarly journals The effects of stress and glucocorticoids on vocalizations: a test in North American red squirrels

2019 ◽  
Vol 30 (4) ◽  
pp. 1030-1040 ◽  
Author(s):  
Matt Sehrsweeney ◽  
David R Wilson ◽  
Maggie Bain ◽  
Stan Boutin ◽  
Jeffrey E Lane ◽  
...  
Keyword(s):  
Stress State ◽  
North American ◽  
Physiological Stress ◽  
Physiological State ◽  
Public Information ◽  
Tamiasciurus Hudsonicus ◽  
Red Squirrels ◽  
Acoustic Structure ◽  
North American Red Squirrels ◽  
Important Means

AbstractAcoustic signaling is an important means by which animals communicate both stable and labile characteristics. Although it is widely appreciated that vocalizations can convey information on labile state, such as fear and aggression, fewer studies have experimentally examined the acoustic expression of stress state. The transmission of such public information about physiological state could have broad implications, potentially influencing the behavior and life-history traits of neighbors. North American red squirrels (Tamiasciurus hudsonicus) produce vocalizations known as rattles that advertise territorial ownership. We examined the influence of changes in physiological stress state on rattle acoustic structure through the application of a stressor (trapping and handling the squirrels) and by provisioning squirrels with exogenous glucocorticoids (GCs). We characterized the acoustic structure of rattles emitted by these squirrels by measuring rattle duration, mean frequency, and entropy. We found evidence that rattles do indeed exhibit a “stress signature.” When squirrels were trapped and handled, they produced rattles that were longer in duration with a higher frequency and increased entropy. However, squirrels that were administered exogenous GCs had similar rattle duration, frequency, and entropy as squirrels that were fed control treatments and unfed squirrels. Our results indicate that short-term stress does affect the acoustic structure of vocalizations, but elevated circulating GC levels do not mediate such changes.

scholarly journals Indirect effects on fitness between individuals that have never met via an extended phenotype

2018 ◽  
Author(s):  
David N. Fisher ◽  
Jessica A. Haines ◽  
Stan Boutin ◽  
Ben Dantzer ◽  
Jeffrey E. Lane ◽  
...  
Keyword(s):  
Population Dynamics ◽  
North American ◽  
Indirect Effects ◽  
Tamiasciurus Hudsonicus ◽  
Extended Phenotype ◽  
Red Squirrels ◽  
Lifetime Fitness ◽  
The Past ◽  
North American Red Squirrels ◽  
The Individual

AbstractInteractions between organisms are ubiquitous and have important consequences for phenotypes and fitness. Individuals can even influence those they never meet, if they have extended phenotypes which mean the environments others experience are altered. North American red squirrels (Tamiasciurus hudsonicus) guard food hoards, an extended phenotype that typically outlives the individual and is almost always inherited by non relatives. Hoarding by previous owners can therefore influence subsequent owners. We found that red squirrels bred earlier and had higher lifetime fitness if the previous owner was a male. This was driven by hoarding behaviour, as males and mid-aged squirrels had the largest hoards, and these effects persisted across owners, such that if the previous owner was male or died in mid-age subsequent occupants had larger hoards. Individuals can, therefore, influence each other’s resource dependent traits and fitness without meeting via extended phenotypes, and so the past can influence contemporary population dynamics.

scholarly journals Glucocorticoids coordinate changes in gut microbiome composition in wild North American red squirrels

2021 ◽  
Author(s):  
Lauren Petrullo ◽  
Tiantian Ren ◽  
Martin Wu ◽  
Rudy Boonstra ◽  
Rupert Palme ◽  
...  
Keyword(s):  
Microbial Diversity ◽  
North American ◽  
Gut Microbiome ◽  
Pathogenic Bacteria ◽  
Experimental Studies ◽  
Ecological Framework ◽  
Ecological Change ◽  
Red Squirrels ◽  
Microbiome Diversity ◽  
North American Red Squirrels

Gut microbiome diversity plays an important role in host health and fitness, in part through the diversification of gut metabolic function and pathogen protection. Elevations in glucocorticoids (GCs) appear to reduce gut microbiome diversity in experimental studies, suggesting that a loss of microbial diversity may be a negative consequence of increased GCs. However, given that ecological factors like food availability and population density may independently influence both GCs and microbial diversity, understanding how these factors structure the GC-microbiome relationship is crucial to interpreting its significance in wild populations. Here, we used an ecological framework to investigate the relationship between GCs and gut microbiome diversity in wild North American red squirrels (Tamiasciurus hudsonicus). We found that higher GCs predicted lower gut microbiome diversity and an increase in metabolic taxa. In addition, we identified a loss of potentially pathogenic bacteria with increasing GCs. Both dietary heterogeneity and an upcoming masting event exhibited direct effects on gut microbiome diversity, whereas conspecific density and host reproductive activity impacted diversity indirectly via changes in GCs. Together, our results suggest that GCs coordinate the effects of ecological change and host biology on gut microbiome diversity, and highlight the importance of situating the GC-microbiome relationship within an ecological framework.

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