Population dynamics of a migrant songbird : do we need to monitor the entire breeding season?

Populations of Clethrionomys rutilus were studied on two islands (Island 2 and Green Island) in the Mackenzie River during the summers of 1976 to 1978. This was done to examine the demographic parameters related to confinement of northern red-backed vole populations on islands.The number of voles on Island 2 in 1977 increased until late June and then remained nearly constant until trapping ceased in late August. On Green Island in 1977 and 1978 and Island 2 in 1978, populations grew all summer and even in August had not reached the densities found during the 1977 high on Island 2. Island 2 in 1977 had an unusually low number of maturing young voles. Higher wounding rates and shorter adjusted range lengths were associated with higher population densities.Although high densities of voles were reached early in the summer of 1977 on Island 2, numbers stopped increasing before the end of the breeding season. Restraint of growth potential was seen in poor maturation of the young and in declining juvenile survival and recruitment of young through summer.

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The ecology of the deer mouse Peromyscus maniculatus in a coastal coniferous forest. I. Population dynamics

Canadian Journal of Zoology ◽

10.1139/z74-015 ◽

1974 ◽

Vol 52 (1) ◽

pp. 107-118 ◽

Cited By ~ 14

Author(s):

B. G. Petticrew ◽

R. M. F. S. Sadleir

Keyword(s):

Population Dynamics ◽

Breeding Season ◽

Deer Mouse ◽

Coniferous Forest ◽

Deer Mice ◽

Population Parameters ◽

Male Behavior ◽

Mature Forest ◽

Live Trapping ◽

Breeding Seasons

A 3-year live-trapping study of deer mice was carried out on separate 1-hectarc (ha) grids located in a mature forest, a recently logged area, and a young plantation. Despite apparent gross differences in the habitats, populations on the recently logged area were similar in numbers, survival, and recruitment to those in the mature forest. There were greater differences in population parameters between years than between these two areas. Populations of deer mice in the young plantation were lower in numbers and eventually went to extinction in the summer of 1970. This appeared to be due rather to the presence of numerous Microtus oregoni in this area than to the habitat being less suitable for deer mice.On the basis of this and previous studies it is proposed that the numbers of deer mice in a population are regulated as follows. During breeding seasons the numbers of males and juveniles are regulated by agonistic male behavior while the numbers of females may be a function of the length of the breeding season. During non-breeding seasons the changes in numbers of all deer mice are regulated by the length of such seasons.

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Sexual maturity, factors affecting the breeding season and breeding in consecutive seasons in populations of overabundant Victorian koalas (Phascolarctos cinereus)

Australian Journal of Zoology ◽

10.1071/zo06015 ◽

2006 ◽

Vol 54 (6) ◽

pp. 385 ◽

Cited By ~ 21

Author(s):

Natasha McLean ◽

Kathrine A. Handasyde

Keyword(s):

Population Dynamics ◽

Breeding Season ◽

Sexual Maturity ◽

Island Population ◽

Population Parameters ◽

Free Living ◽

Phascolarctos Cinereus ◽

Factors Affecting ◽

Reproductive Patterns ◽

South West

It is important to have knowledge of basic population parameters to understand how these vary geographically and temporally and how they contribute to population dynamics. This paper investigates three of these parameters in Victorian koala populations: sexual maturity, aspects of the breeding season, and the continuity of individuals’ breeding. The investigation was carried out in koalas of known-age in two free-living (Redbill Creek on French Island and Brisbane Ranges) and one semi-captive (the Koala Conservation Centre on Phillip Island) population as well as koalas of unknown age in four Victorian populations of overabundant koalas: Mt Eccles and Framlingham in south-west Victoria, French Island in Western Port and Snake Island in south Gippsland. At sexual maturity, female koalas had a mean age (±95% confidence interval) of 24.4 months (23.5–25.3 months), a mean head length of 125 mm (124–127 mm) and a mean body mass of 6.6 kg (6.3–6.8 kg). Only 7.4% of independent females (of unknown age) were carrying young when they weighed less than 6 kg. The breeding season was more restricted in the south-west populations. At Framlingham and Mt Eccles 85% and 91% of births, respectively, occurred between December and March. At Snake and French Islands only 46% and 53% of births, respectively, were recorded in the same period. In the Chlamydia-free population (Red Bill Creek) none of the koalas that were monitored stopped breeding and then resumed breeding in a subsequent season whereas many females from Chlamydia-infected populations (Brisbane Ranges and the Koala Conservation Centre) did so. This variation in reproductive patterns is likely to make an important contribution to the variation in the demography observed in different koala populations.

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Effects of predation and rabbit haemorrhagic disease on population dynamics of rabbits (Oryctolagus cuniculus) in North Canterbury, New Zealand

Wildlife Research ◽

10.1071/wr00088 ◽

2002 ◽

Vol 29 (6) ◽

pp. 627 ◽

Cited By ~ 20

Author(s):

Ben Reddiex ◽

Graham J. Hickling ◽

Grant L. Norbury ◽

Chris M. Frampton

Keyword(s):

Population Dynamics ◽

New Zealand ◽

Breeding Season ◽

Predator Control ◽

Zealand Rabbit ◽

Rabbit Haemorrhagic Disease ◽

Low Levels ◽

Haemorrhagic Disease ◽

The Impact ◽

Very High

The impact of predation and rabbit haemorrhagic disease (RHD) on population dynamics of rabbits, and the survival of juvenile rabbits, was investigated between July 1999 and March 2000 in North Canterbury, New Zealand. Rabbit abundance and pre- and post-emergent rabbit mortality were monitored on four sites, two of which were subject to predator control. RHD spread naturally through all sites from late November to early December. Rabbit densities declined on all sites, but after the RHD epidemic, declines were significantly greater where populations of predators had not been controlled. Survival of rabbit nestlings was lower where predators were not controlled. All post-emergent radio-collared rabbits died at sites where predators were not controlled, whereas 18% of those collared at sites where predators were controlled survived to maturity. In contrast to the results from previous studies, rabbits born at the start of the breeding season had very high rates of post-emergent mortality, as they appeared to be susceptible to the RHD virus later in the breeding season. The age at which juvenile rabbits become susceptible to RHD, the timing of RHD epidemics, and the abundance of predators are likely to be important in determining survival of juvenile rabbits. This study demonstrates that predation can reduce rabbit populations to low levels, but only in combination with other factors, in this case RHD.

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Population dynamics of the black-cheeked gnateater (Conopophaga melanops, Conopophagidae) in southern Brazil

Journal of Tropical Ecology ◽

10.1017/s0266467409990289 ◽

2009 ◽

Vol 25 (6) ◽

pp. 605-613 ◽

Cited By ~ 3

Author(s):

André Magnani Xavier de Lima ◽

James Joseph Roper

Keyword(s):

Population Dynamics ◽

Population Growth ◽

Breeding Season ◽

Survival Rates ◽

Territory Size ◽

Adult Survival ◽

Southern Brazil ◽

Annual Survival ◽

Socially Monogamous ◽

Population Structure And Dynamics

Abstract:Population structure and dynamics of the black-cheeked gnateater (Conopophaga melanops) were studied at Salto Morato Nature Reserve, in Paraná, southern Brazil, from October 2006 to September 2007. Territory size and population density, breeding season (timing and length), reproductive success and annual survival rates were estimated from sightings of 18 marked adult birds and the success of 18 nesting attempts. The black-cheeked gnateater is socially monogamous and territorial, with a breeding-season length of approximately 3 mo beginning in early October. Predation caused most nest failures, nest survival was 0.96 d−1and apparent annual nesting success was 22%, resulting in annual productivity of 0.36 individuals per adult. Apparent adult annual survival was ~0.44 y−1. Seventy-five per cent of fledglings survived at least 2 mo after fledging. Two methods of estimating population growth rate suggest very different rates: r = −0.04 (~ stable), or λ varies between 0.475–0.616 (declining). Yet, low apparent adult survival suggests that territories are not permanent, perhaps abandoned after nest failure. We find that by estimating population growth, even in short-term studies, testable hypotheses can be generated that will allow better understanding of population dynamics.

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The population dynamics of Lepeophtheirus pectoralis (Müller): seasonal variation in abundance and age structure

Parasitology ◽

10.1017/s0031182000063058 ◽

1974 ◽

Vol 69 (3) ◽

pp. 361-371 ◽

Cited By ~ 20

Author(s):

G. A. Boxshall

Keyword(s):

Population Dynamics ◽

Seasonal Variation ◽

Breeding Season ◽

Age Structure ◽

Egg Production ◽

Parasite Population ◽

Intensity Of Infection ◽

Second Mode ◽

Maturation Rate ◽

Alternation Of Generations

The ectoparasitic copepod Lepeophtheirus pectoralis exhibited a regular annual cycle of abundance on its hosts. Both the incidence and intensity of infection were greatest in August or September and both declined over winter to their minimum values in April. Very similar cycles were observed in both 1972 and 1973. Analysis of the age structure of the parasite population showed that the increase in abundance coincided with the onset of the breeding season. Although females always outnumbered males the sex ratio approached unity during the breeding season, which extended from May to October. Copulating pairs were most commonly observed during this period.There was a marked bimodal peak of egg production each year, with the first mode occurring around May and the second mode around August or September. This pattern was produced by a system of alternation of generations operating within the parasite population, with a summer type generation (distinguishable by its rapid maturation rate and reduced longevity) alternating with an overwintering type of generation.

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Reproduction and population dynamics of Leptochela gracilis (Decapoda: Pasiphaeidae) on the western coast of Korea, Yellow Sea

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315406012914 ◽

2006 ◽

Vol 86 (1) ◽

pp. 113-120 ◽

Cited By ~ 1

Author(s):

C.W. Oh ◽

J.Y. Kim ◽

I.J. Jeong ◽

H.L. Suh ◽

Y.K. Cho

Keyword(s):

Population Dynamics ◽

Breeding Season ◽

Yellow Sea ◽

Gonadosomatic Index ◽

Dry Weight ◽

Western Coast ◽

Multiple Spawning ◽

Significant Difference ◽

Monthly Changes ◽

Size At Age

Investigations were made on reproduction and population dynamics of Leptochela gracilis on the western coast of Korea, Yellow Sea, between May 2000 and October 2001. The egg volume was significantly larger at later egg stage than at early egg stage. Brood loss did not occur during the incubation period. Based on dry weight, the reproductive output (mass of incubating eggs/mass of female) averaged 0.18. The mature females first appeared in May, reached a peak in July and August, and then did not appear after September. The main breeding season was summer, although slightly different between the two years. A similar pattern could be found in monthly changes of gonadosomatic index (GSI), showing relatively higher GSI during the annual breeding season. A significant difference in ovarian dry weight between females with non-eyed eggs and eyed eggs indicates that ovarian maturation occurred during the embryonic development, suggesting that females were potentially consecutive breeders, capable of multiple spawning within a reproductive season. The size at which 50% of females were mature (CL50) was estimated as 7.63 mm carapace length. Females grew faster and reached a larger size at age than males (L∞=12.43 mm CL and K=0.90 y−1 for females, and L∞=12.22 mm CL and K=0.58 y−1 for males).

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