Spatial structure of harbour seal populations and the implications thereof

2001 ◽  
Vol 79 (12) ◽  
pp. 2115-2127 ◽  
Author(s):  
T Härkönen ◽  
K C Harding
Keyword(s):  
Population Dynamics ◽  
Site Fidelity ◽  
Phoca Vitulina ◽  
Population Increase ◽  
Dynamic Processes ◽  
Term Study ◽  
Long Term Study ◽  
Harbour Seals ◽  
Age And Sex

A long-term study of freeze-branded harbour seals (Phoca vitulina) revealed explicit site fidelity. Individuals were followed up to 14 years of age and none of the 163 branded animals were observed to haul out beyond a 32-km distance from the site where they were branded as pups. Within this range, striking spatial segregation by age and sex prevailed. While females' site fidelity increased with age, males spent less time at their natal site with increasing age. These findings have consequences for understanding the population dynamics of harbour seals, since single "colonies" will act as partly isolated "subpopulations" in some contexts but not in others. The differing migration tendencies of the population segments lead to spatially segregated sex and age ratios of subpopulations and create a complex pattern of connectivity among these subpopulations. Ignoring the spatial scale will lead to severe misinterpretations of analyses of basic population-dynamic processes, especially rates of population increase, rates of gene flow, and the dynamics of the spread of diseases. We suggest that when studies have different aims, these should be addressed by encompassing different numbers of subpopulations.

scholarly journals Climatic Factors, Reproductive Success and Population Dynamics in the Montane Vole, Microtus montanus

1991 ◽  
Vol 15 ◽  
pp. 162-164
Author(s):  
Aelita Pinter
Keyword(s):  
Population Dynamics ◽  
Reproductive Success ◽  
Population Density ◽  
Environmental Variables ◽  
Climatic Factors ◽  
Small Rodents ◽  
Term Study ◽  
Microtus Montanus ◽  
Long Term Study

Multiannual fluctuations in population density ("cycles") of small rodents have been known since antiquity (Elton 1942). Numerous hypotheses have been proposed to explain this phenomenon (for reviews see Finerty 1980, Taitt and Krebs 1985). However, none of these hypotheses, alone or in combination, have been able to explain the causality of cycles. The objectives of this long-term study are to determine whether environmental variables, possibly acting through reproductive responses, contribute to the multiannual fluctuations of the montane vole, Microtus montanus.

scholarly journals Climatic Factors, Reproductive Success and Population Dynamics in the Montane Vole, Microtus montanus

1987 ◽  
Vol 11 ◽  
pp. 103-105
Author(s):  
Aelita Pinter
Keyword(s):  
Population Dynamics ◽  
Reproductive Success ◽  
Population Density ◽  
Environmental Variables ◽  
Climatic Factors ◽  
Small Rodents ◽  
Term Study ◽  
Microtus Montanus ◽  
Long Term Study

Multiannual fluctuations in population density of small rodents have been known since antiquity. However, factors responsible for this phenomenon remain unknown (Krebs and Myers 1974, Finerty 1980, Taitt and Krebs 1985). The objectives of this long-term study are to determine whether environmental variables, possibly acting through reproductive responses, contribute to the multiannual fluctuations of the montane vole, Microtus montanus.

scholarly journals Climatic Factors, Reproductive Success and Population Dynamics in the Montane Vole, Microtus montanus

1988 ◽  
Vol 12 ◽  
pp. 121-124
Author(s):  
Aelita Pinter
Keyword(s):  
Population Dynamics ◽  
Reproductive Success ◽  
Population Density ◽  
Environmental Variables ◽  
Climatic Factors ◽  
Small Rodents ◽  
Term Study ◽  
Microtus Montanus ◽  
Long Term Study

Multiannual fluctuations in population density ("cycles") of small rodents have been known since antiquity (Elton 1942). Numerous hypotheses have been proposed to explain this phenomenon (for reviews see Krebs and Myers 1974, Finery 1980, Taitt and Krebs 1985). However, none of these hypotheses, alone or in combination, can explain the causality of cycles. The objectives of this long-term study are to determine whether environmental variables, possibly acting through reproductive responses, contribute to the multiannual fluctuations of the montane vole, Microtus montanus.

scholarly journals Climatic Factors, Reproductive Success and Population Dynamics in the Montane Vole, Microtus montanus

1997 ◽  
Vol 21 ◽  
pp. 57-59
Author(s):  
Aelita Pinter
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
National Park ◽  
Climatic Factors ◽  
Term Study ◽  
Microtus Montanus ◽  
Long Term Study ◽  
Small Measure ◽  
Long Term Studies

Multiannual fluctuations ("cycles") in population density of small rodents doubtless result from the interaction of a multitude of factors, as evidenced by the variety of hypotheses proposed to explain the phenomenon (for reviews see Finerty 1980, Taitt and Krebs 1985). However, the inability of these hypotheses - alone or in combination - to explain the causality of cycles rests in no small measure with the fact that long-term studies of the phenomenon are notoriously uncommon. The objectives of this project are to continue a long-term study of the population dynamics of the montane vole, Microtus montanus, in Grand Teton National Park. On the basis of earlier observations (Pinter 1986, 1988) particular emphasis will be placed on how environmental variables, possibly acting through reproductive responses, contribute to the population density cycles of these rodents.

scholarly journals Climatic Factors, Reproductive Success and Population Dynamics in the Montane Vole, Microtus montanus.

2003 ◽  
Vol 27 ◽  
pp. 42-44
Author(s):  
Aelita Pinter
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
National Park ◽  
Climatic Factors ◽  
Term Study ◽  
Microtus Montanus ◽  
Long Term Study ◽  
Small Measure ◽  
Long Term Studies

A variety of hypotheses have been proposed to explain multiannual fluctuations in population density ("cycles") of small rodents (for reviews see Finerty 1980, Taitt and Krebs 1985). Doubtless, such cycles - known since antiquity (Elton 1942) - result from an interaction of a multitude of factors. However, the inability of extant hypotheses, alone or in combination, to explain the causality of cycles rests in no small measure with the fact that long-term studies of the phenomenon are notoriously uncommon. The objectives of this project are to continue the long-term study of population dynamics of the montane vole, Microtus montanus, in Grand Teton National Park. Earlier observations (Pinter 1986, 1988) indicate that environmental variables might contribute to the population density cycles of these rodents, possibly by influencing their growth and various aspects of their reproduction.

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