Costs of escalated territorial defence in red squirrels

1994 ◽  
Vol 72 (6) ◽  
pp. 1162-1167 ◽  
Author(s):  
A. Kari Stuart-Smith ◽  
Stan Boutin
Keyword(s):  
Foraging Behaviour ◽  
Reproductive Status ◽  
Tamiasciurus Hudsonicus ◽  
Territorial Disputes ◽  
Theoretical Studies ◽  
Reproductive Costs ◽  
Sunflower Seeds ◽  
Territorial Defence ◽  
Red Squirrels ◽  
And Control

The costs of escalated territorial defence have not been well-documented, although in theoretical studies they are often assumed to be high. We manipulated territorial defence in red squirrels (Tamiasciurus hudsonicus) to assess the costs of territorial disputes in terms of energy, reproductive status, and predation. Feeders containing sunflower seeds were used to manipulate foraging behaviour and induce territorial disputes. Experimental squirrels displayed dramatically higher rates of territorial behaviours in response to feeders, and while there was no difference in survival between experimental and control squirrels, in 4 of the 17 disputes territory owners lost their territories. All 3 females that did so suffered reproductive costs. Territorial disputes were won by the heavier squirrels in all 12 cases where contestants were of different masses, but where the contestants were of similar masses (4 of 5 cases), territory owners were more likely to win.

scholarly journals Red squirrels mitigate costs of territory defence through social plasticity

2018 ◽  
Author(s):  
Erin R. Siracusa ◽  
David R. Wilson ◽  
Emily K. Studd ◽  
Stan Boutin ◽  
Murray M. Humphries ◽  
...  
Keyword(s):  
Social Environment ◽  
Tamiasciurus Hudsonicus ◽  
Social Environments ◽  
Territorial Defence ◽  
Cross Sectional ◽  
Red Squirrels ◽  
Multiple Observations ◽  
Territory Defence ◽  
Social Plasticity ◽  
Post Hoc

AbstractFor territorial species, the ability to be behaviourally plastic in response to changes in their social environment may be beneficial by allowing individuals to mitigate conflict with conspecifics and reduce the costs of territoriality. Here we investigated whether North American red squirrels (Tamiasciurus hudsonicus) were able to minimize costs of territory defence by adjusting behaviour in response to the familiarity of neighbouring conspecifics. Since red squirrels living in familiar neighbourhoods face reduced intrusion risk, we predicted that increasing familiarity among territorial neighbours would allow squirrels to spend less time on territorial defence and more time in the nest. Long-term behavioural data (1995-2004) collected from the same squirrels across several different social environments indicated that red squirrels reduced rates of territorial vocalizations and increased nest use in response to increasing familiarity with neighbours. In contrast, cross-sectional data (2015-2016), which provided observations from each individual in a single social environment, did not provide evidence of this plasticity. Post-hoc analyses revealed that evidence of social plasticity in this system was primarily due to within-individual changes in behaviour, which we were unable to estimate in the cross-sectional data. Our results demonstrate that red squirrels can reduce the costs of territoriality by appropriately adjusting behaviour in response to changes in their social environment. However, our results also suggest that estimating plasticity by comparing behaviour among individuals (i.e. cross-sectional analyses) may not always be reliable. Our ability to detect these effects may therefore depend on having data with multiple observations from the same individuals across different social environments.

Winter food habits and foraging behaviour of fishers (Martes pennanti) and martens (Martes americana) in southeastern Manitoba

1987 ◽  
Vol 65 (3) ◽  
pp. 745-747 ◽  
Author(s):  
R. Michael Raine
Keyword(s):  
Food Habits ◽  
Foraging Behaviour ◽  
Martes Americana ◽  
Tamiasciurus Hudsonicus ◽  
Martes Pennanti ◽  
Red Squirrels ◽  
Snowshoe Hares ◽  
Pine Martens ◽  
Winter Food ◽  
Frequency Occurrence

A tracking study of fishers, Martes pennanti, and American pine martens, Martes americana, conducted over two winters in southeastern Manitoba showed that both species preyed heavily on snowshoe hares, Lepus americanus, during a period of hare abundance. Fishers had an 84.3% frequency occurrence (n = 159) of hares in their scats, while martens had a frequency occurrence of 58.9% (n = 107). Martens had a higher frequency of microtincs and red squirrels, Tamiasciurus hudsonicus, in their diets than did fishers. This difference was reflected in the foraging behaviour of the two species, with martens exhibiting more subnivean and arboreal behaviour than fishers.

scholarly journals Influence of Fertilization on Feeding Attacks to Lodgepole Pine by Snowshoe Hares and Red Squirrels

1982 ◽  
Vol 58 (6) ◽  
pp. 263-266 ◽  
Author(s):  
Thomas P. Sullivan ◽  
Druscilla S. Sullivan
Keyword(s):  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Growth And Yield ◽  
Tamiasciurus Hudsonicus ◽  
Average Amount ◽  
Red Squirrels ◽  
Animal Damage ◽  
Snowshoe Hares ◽  
Yield Responses ◽  
And Control

Lodgepole pine (Pinus contorta Dougl.) shows favourable growth and yield responses to spacing (thinning) and potentially to fertilization, but is susceptible to feeding injuries by snowshoe hares (Lepus americanus Erxleben) and red squirrels (Tamiasciurus hudsonicus Erxleben). This study was designed to determine the incidence of animal damage to crop trees in a fertilized-spaced stand, compared with those in spaced only and control (unspaced) stands. There was little variation in the percentage of crop trees (range 53.6% to 63.3%) damaged by hares in the three stands. Hares removed an average of 92.2 cm2 of bark and associated vascular tissues per attack from fertilized stems compared with 46.2 cm2 in the spaced only stand. This latter value was nearly double that recorded in the control stand (27.4 cm2). Squirrels damaged more fertilized trees (38.9%) than trees in the spaced (30.9%) or control (14.3%) stands. Squirrels removed the largest average amount of bark (66.9 cm2) per attack from fertilized stems with little difference between spaced (41.6 cm2) and control (42.3 cm2) stands. We conclude that hares and squirrels clearly prefer to feed on fertilized lodgepole pine stems over those in non-fertilized or un-managed stands.

Poland

2018 ◽  
Author(s):  
Andrew A. Michta
Keyword(s):  
Armed Forces ◽  
The European Union ◽  
Territorial Defence ◽  
Eastern Flank ◽  
Security Environment ◽  
North Eastern ◽  
And Control ◽  
The Impact ◽  
Command And Control System ◽  
T State

This chapter analyses the adaptation of Poland’s defence policy and armed forces to the rapidly changing security environment along NATO’s north-eastern flank. First, it examines the impact of a resurgent Russia on Poland’s security calculus, especially since Russia’s seizure of Crimea and the war in eastern Ukraine. Next, it addresses the evolution of Warsaw’s views on the relative utility of NATO and the European Union and its efforts to return NATO to its traditional territorial defence role. It then focuses on the modernization of Poland’s armed forces, with a special emphasis on doctrinal change, the reform of the command and control system, and the creation of the Territorial Defence units. It also reviews the t state of key hardware purchases as of mid-2017. The chapter concludes with an overall assessment of the level of capabilities and the readiness of the armed forces in the changing threat environment along NATO’s north-eastern flank.

scholarly journals Potential of Small Culverts as Wildlife Passages on Forest Roads

2021 ◽  
Vol 13 (13) ◽  
pp. 7224
Author(s):  
Hsiang-Ling Chen ◽  
Erin E. Posthumus ◽  
John L. Koprowski
Keyword(s):  
Animal Movement ◽  
Small Dimension ◽  
Lynx Rufus ◽  
Tamiasciurus Hudsonicus ◽  
Red Squirrels ◽  
Forest Roads ◽  
Alternative Pathways ◽  
Slow Moving ◽  
Trail Cameras ◽  
Spermophilus Variegatus

Roads and traffic can cause animal mortality. Specifically, roads serve as barriers by impeding animal movement, resulting in demographic and genetic consequences. Drainage structures, such as culverts, can provide linkages between habitat patches. However, the potential of small culverts with diameters of <60 cm (e.g., wildlife passages that facilitate movement on forest roads) are relatively unknown. In this study, we used trail cameras to monitor the use of 14 small culverts, by mammals, along forest roads on Mt. Graham, home of the critically endangered Mt. Graham red squirrels (Tamiasciurus hudsonicus grahamensis), in southeastern Arizona, USA. From 2011 to 2013, we only recorded 20 completed road crossings through culverts. More than half of culvert uses were by striped skunks (Mephitis mephitis), followed by the rock squirrel (Spermophilus variegatus) and the bobcat (Lynx rufus). The Mt. Graham red squirrel was the only species that was common along the roads, but never crossed the roads. Culverts with higher usages were characterized by shorter culvert lengths and absence of accumulated soil inside the culverts. Our study shows that small-dimension drainage systems may provide alternative pathways for wildlife crossing roads, especially for slow moving and ground dwelling species. However, the potential of small culverts assisting wildlife crossings can only be maximized when culverts are accessible year-round.

Jack pine cone quality and cache sizes of red squirrels in southern New Brunswick, Canada

1997 ◽  
Vol 75 (2) ◽  
pp. 332-335 ◽  
Author(s):  
Michael A. Setterington ◽  
Daniel M. Keppie
Keyword(s):  
New Brunswick ◽  
Pinus Banksiana ◽  
Seed Mass ◽  
Dry Mass ◽  
Jack Pine ◽  
Tamiasciurus Hudsonicus ◽  
Red Squirrels ◽  
Length Width ◽  
Total Seed ◽  
Number Of Seeds

Relationships between external cone characteristics (length, width, wet and dry mass), cone quality (total seed mass as a proportion of cone mass, total number of seeds per cone, total seed mass per cone), and number of cones in caches were evaluated for caches of jack pine (Pinus banksiana) cones belonging to red squirrels (Tamiasciurus hudsonicus) in two plantations in southern New Brunswick. Cone length and mass were good predictors of the total number of seeds per cone and total seed mass per cone. Length accounted for a small proportion of the variance of total seed mass as a proportion of cone mass. There was no relationship between the number of seeds or total seed mass per cone and the number of cones per cache.

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.

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.

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