VIABILITY OF WHITE SPRUCE SEED FROM SQUIRREL-CUT CONES

1964 ◽  
Vol 40 (1) ◽  
pp. 98-110 ◽  
Author(s):  
J. W. Bruce Wagg
Keyword(s):  
Picea Glauca ◽  
Seed Viability ◽  
White Spruce ◽  
Mature Seed ◽  
Tamiasciurus Hudsonicus ◽  
Red Squirrel ◽  
Red Squirrels

A study was made of the viability of white spruce, Picea glauca, seed obtained from seven cone caches of red squirrels, Tamiasciurus hudsonicus. Habits of the red squirrel, relation of seed viability to cone-caching activities and the relation of viability of seed obtained from the cached cones to the cones on the trees are described.Viability of see from cached cones does not vary between the time squirrels began to cache cones in quantity and the time the last cones are cached. Seed from the cached cones showed a higher percentage of viability than seed of cones collected from trees, because some of the mature seed had fallen from the partially open cones on the trees resulting in an increase in the percentage of undeveloped seed in progressive cone collections.

Pre-dispersal seed predation of white spruce cones in logged boreal mixedwood forest

2003 ◽  
Vol 33 (1) ◽  
pp. 33-40 ◽  
Author(s):  
Susan Peters ◽  
Stan Boutin ◽  
Ellen Macdonald
Keyword(s):  
Seed Predation ◽  
Picea Glauca ◽  
Natural Regeneration ◽  
White Spruce ◽  
Tamiasciurus Hudsonicus ◽  
Red Squirrels ◽  
Tree Crowns ◽  
Tree Retention ◽  
Boreal Mixedwood Forest ◽  
Mixedwood Boreal Forest

Predation of white spruce (Picea glauca (Moench) Voss) cones by red squirrels (Tamiasciurus hudsonicus Erxleben) was quantified in the mixedwood boreal forest of Alberta in cutblocks with seed tree retention and in adjacent uncut forest, during 3 years with varying levels of cone crop (1998, 1999, 2000). Percent cone loss was quantified by comparison of paired pre- and post-caching photographs of tree crowns. Cone loss from seed trees in cutblocks was significantly lower than from control trees in adjacent uncut forest (48.5 vs. 54.9%). Although the number of cones produced per tree declined by 42% and the percentage of trees producing cones declined by approximately 48% between 1998 and 2000, there was no corresponding increase in the percentage of cones harvested by squirrels. Percent cone loss was significantly lower from single seed trees in cutblocks, as compared with seed trees left in patches of more than 20 trees (33.4 vs. 50.5%). Cone predation significantly reduced the amount of seed available for natural regeneration using a seed tree system. Although blowdown may be reduced if seed trees are left in patches, leaving white spruce seed trees as singles in cutblocks may reduce the level of cone predation.

scholarly journals Seed masting causes fluctuations in optimum litter size and lag load in a seed predator

2018 ◽  
Author(s):  
Andrew McAdam ◽  
Stan Boutin ◽  
Ben Dantzer ◽  
Jeff Lane
Keyword(s):  
Litter Size ◽  
Picea Glauca ◽  
Life Histories ◽  
Local Density ◽  
White Spruce ◽  
Tamiasciurus Hudsonicus ◽  
Seed Predator ◽  
Red Squirrels ◽  
Seed Predators ◽  
Seed Crops

The episodic production of large seed crops by some perennial plants, is referred to as masting and is known to increase seed escape by alternately starving and swamping seed predators. These pulses of resources, however, might also act as an agent of selection on the life histories of seed predators, which could indirectly enhance seed escape by inducing an evolutionary load on seed predator populations. Lag loads in seed predators could result from mast-induced shifts in optimum phenotypes that exceed the capacity of seed predators to adaptively track optimum phenotypes through phenotypic plasticity. Alternatively, masting could generate mismatches in selection across generations, where adaptation to the parental environment leads to maladaptation in the offspring environment. Here we measured natural selection on female North American red squirrels (Tamiasciurus hudsonicus) across 28 years and five white spruce (Picea glauca) masting events. Red squirrel litter sizes were similar to optimum litter sizes during non-mast years, but were well below optimum litter sizes during resource-rich mast years. Mast events, therefore caused selection for larger litters (B = 0.25) and a lag load (L = 0.25) on red squirrels during mast years. Furthermore, we found that the annual fitness of spruce trees was negatively related to the local density of squirrels during mast years, indicating that the observed lag load on squirrels enhanced the number of spruce cones escaping squirrel predation. Although, the frequency of mast events and the demography of red squirrels were such that offspring and parents often experienced opposite environments with respect to the mast, we found no effect of environmental mismatches across generations on either offspring survival or population growth. Instead, squirrels plastically increased litter sizes in anticipation of mast events, which partially, although not completely, reduced the lag load resulting from this change in food availability. Variable selection on litter size caused by white spruce mast events, therefore, induced a lag load on the population of red squirrels that was not affected by whether individual squirrels were born during mast (matching) or non-mast (mismatching) conditions.

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.

Maturity and Viability of Seed From Squirrel-Cut Pine Cones

1987 ◽  
Vol 63 (4) ◽  
pp. 268-271 ◽  
Author(s):  
T. A. Hurly ◽  
R. J. Robertson ◽  
C. W. Yeatman
Keyword(s):  
Key Words ◽  
Scots Pine ◽  
Seed Viability ◽  
Seed Orchard ◽  
Red Squirrel ◽  
Natural Forests ◽  
Red Squirrels ◽  
Seed Maturity ◽  
Acceptable Quality ◽  
Pine Cones

The viability of pine seed from cones cached by red squirrels was compared with the viability of seed collected weekly during August and September. Scots pine seed collected during the last three weeks of August exhibited poor but increasing germinability (24.3% – 77.0%), but seed collected in September showed high germinability (95.0% – 99.5%). The strategy of collecting cones before intensive harvesting by squirrels is therefore of limited utility. Scots, red, and jack pine cones recovered from squirrel caches yielded seed of acceptable quality (greater than 80% germinability in 9 of 10 collections). Recovering cones from squirrel caches is a practical and viable strategy in seed orchards and natural forests. We recommend that collections be made within one month of harvesting by the squirrels. Key words: pine seed, seed viability, seed maturity, seed orchard red squirrel management.

Genetic structure of the arboreal squirrels (Glaucomys sabrinus and Tamiasciurus hudsonicus) in the North American Black Hills

2012 ◽  
Vol 90 (9) ◽  
pp. 1191-1200 ◽  
Author(s):  
A.M. Kiesow ◽  
E.M. Monroe ◽  
H.B. Britten
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Management Practices ◽  
Allelic Diversity ◽  
Black Hills ◽  
Tamiasciurus Hudsonicus ◽  
Glaucomys Sabrinus ◽  
Red Squirrel ◽  
Isolated Populations ◽  
Red Squirrels

We selected two isolated mammalian populations, the Black Hills northern flying squirrel ( Glaucomys sabrinus (Shaw, 1801)) and red squirrel ( Tamiasciurus hudsonicus (Erxleben, 1777)), to elucidate their genetic structure. We trapped both squirrels from 2005 to 2007, in three regions of the Black Hills, differing in geology and vegetation, to collect ear samples for genetic analyses. Microsatellite loci (northern flying (9) and red squirrel (13)) were used to examine genetic structure. Data analyses estimated genetic variability, substructure, and gene flow. Northern flying and red squirrel populations have allelic diversity and observed heterozygosity similar to other isolated populations. Each species shows weak substructure from STRUCTURE and GENELAND analyses, suggesting squirrel movements may be inhibited by topography or unsuitable habitat. Recent gene flow estimates from BAYESASS indicate that both species experience some within population gene flow and red squirrels may be more structured than northern flying squirrels because of lower migration rates. Concordant patterns of genetic structure in northern flying and red squirrels indicate that other species’ movements in the Black Hills may be affected by topography and habitat. Because their habitat is isolated in the Black Hills, management practices and conservation measures are recommended to promote viability and survival of each species.

Body temperature dynamics of the red squirrel (Tamiasciurus hudsonicus): adaptations for energy conservation

1979 ◽  
Vol 57 (7) ◽  
pp. 1349-1354 ◽  
Author(s):  
Ronald W. Pauls
Keyword(s):  
Body Temperature ◽  
Motor Activity ◽  
Energy Conservation ◽  
Outdoor Environment ◽  
Tamiasciurus Hudsonicus ◽  
Rapid Decline ◽  
Red Squirrel ◽  
Red Squirrels ◽  
Air Temperatures ◽  
Temperature Dynamics

Abdominal temperatures (Tb) of two captive female red squirrels (Tamiasciurus hudsonicus) in a natural outdoor environment were monitored by radiotelemetry at air temperatures (Ta) from −33 to 28 °C. Abdominal temperature ranged from 35.9 to 41.4 °C with values usually less than 39 °C when an animal was in the nest and greater than 39 °C when outside. An increase of Tb to about 39 °C usually occurred before an animal left the nest. In the nest Tb was positively correlated with Ta. Outside the nest there was a weak positive correlation at Ta less than 15 °C and a stronger negative correlation at higher Ta. During subnivean activity a rapid decline in Tb usually occurred. It is suggested that in the nest a low Tb is adaptive in that it results in energy conservation while a higher Tb is required outside the nest for rapid and coordinated motor activity.

Behavioural strategies relevant to the energy economy of the red squirrel (Tamiasciurus hudsonicus)

1978 ◽  
Vol 56 (7) ◽  
pp. 1519-1525 ◽  
Author(s):  
Ronald W. Pauls
Keyword(s):  
Locomotor Activity ◽  
Air Temperature ◽  
Activity Patterns ◽  
Tamiasciurus Hudsonicus ◽  
Temperature Cycle ◽  
Red Squirrel ◽  
Red Squirrels ◽  
Time Out ◽  
Energy Economy ◽  
Behavioural Strategies

Amount and intensity of locomotor activity and time out of the nest were measured for a 1-year period on captive red squirrels (Tamiasciurus hudsonicus) under natural conditions. Daily and annual activity patterns and correlations between activity and meteorological variables were examined. A pronounced annual cycle, in phase with the annual temperature cycle, was found in all three aspects of activity. Daily amount of locomotor activity and time out of the nest were closely correlated with mean daily air temperature. Wind, photoperiod, and air temperature during the preceding week showed a weak but significant correlation with activity. Daily patterns of activity varied seasonally from a distinctly bimodal to a unimodal pattern, with a shift in winter to more midday activity. The relevance of these behavioural strategies to the energy economy of the red squirrel is discussed.

Female Red Squirrel (Tamiasciurus hudsonicus) Reproductive Tracts from Fenitrothion Treated and Untreated Forest of Southeastern New Brunswick

1986 ◽  
Vol 62 (4) ◽  
pp. 233-235 ◽  
Author(s):  
Louis LaPierre
Keyword(s):  
New Brunswick ◽  
Coniferous Forest ◽  
Tamiasciurus Hudsonicus ◽  
Corpora Lutea ◽  
Red Squirrel ◽  
Probability Level ◽  
Red Squirrels ◽  
August 15Th ◽  
Student’S T ◽  
Student’S T Test

Between August 15th and September 15th 1979, 1980 and 1981, 77 and 74 red squirrels, Tamiasciurus hudsonicus, were captured within the sprayed and unsprayed coniferous forest of southeastern New Brunswick. Following live capture, the squirrels were sacrificed, weighed and the reproductive tracts were removed and preserved in a 10% formalin solution.Counts of placental scars and corpora lutea of squirrels that inhabited the sprayed forest had a mean placental scar count of 3.8 and a mean corpora lutea count of 4.2. Squirrels from the unsprayed coniferous forest had a mean placental count of 3.6 and a corpora lutea count of 3.9. Statistical analyses, using the student's T-test with a probability level of 0.05, revealed no significant differences in reproductive success of the two groups of squirrels.

Effect of temperature and acclimation upon FFA levels in three species of rodents

1971 ◽  
Vol 49 (3) ◽  
pp. 303-305 ◽  
Author(s):  
J. Homer Ferguson ◽  
G. Edgar Folk Jr.
Keyword(s):  
Cold Acclimation ◽  
Cold Exposure ◽  
Tamiasciurus Hudsonicus ◽  
Effect Of Temperature ◽  
Red Squirrel ◽  
Short Term ◽  
Red Squirrels ◽  
White Rats ◽  
Short Term Exposure ◽  
Rats And Mice

Free fatty acid (FFA) levels were determined in warm- and cold-acclimated white rats, mice, and red squirrels (Tamiasciurus hudsonicus). FFA concentrations of the genetically cold-adapted species (red squirrel) were highest and reflect its ability to maintain high metabolic rates reported by others. In the red squirrels, FFA concentrations were elevated after cold acclimation. Acclimation of white rats and mice had no effect on FFA levels. Short-term cold exposure (−35 °C) caused the FFA levels to rise in all three species. Cold-exposed mice were found to be highest in plasma FFA content. The ability of the red squirrels to mobilize FFA during short-term exposure was enhanced by cold acclimation. The response of rats and mice to cold exposure was not changed by acclimation. This would indicate a greater capacity of the red squirrel to respond to acclimating conditions.

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.

Sign in / Sign up

Export Citation Format

Share Document