Biology of The Southern Brown Bandicoot (Isoodon Obesulus) In South-Eastern Tasmania. II. Demography.

1998 ◽  
Vol 20 (3) ◽  
pp. 339
Author(s):  
S.A. Mallick ◽  
M.M. Driessen ◽  
G.J. Hocking
Keyword(s):  
Sex Ratio ◽  
Significant Decline ◽  
Home Ranges ◽  
Sexually Dimorphic ◽  
South Eastern ◽  
Live Trapping ◽  
Dry Conditions ◽  
Males And Females ◽  
The Mean ◽  
Two Populations

We used live-trapping to study the demography of two populations of the southern brown bandicoot, Isoodon obesulus, in south-eastern Tasmania from March 1992 to March 1995. The bulk of I. obesulus captures were in woodland/forest or within 3 m of its verge, with <10% of captures in 'open' pasture. Densities ranged from 0-0.35 animals/hectare. Both populations underwent a significant decline over the study period. This decline is thought to be the result of the exceptionally dry conditions over the three years of the study. Adult sex ratios (male/female) ranged from 0.6- 1.17. The sex ratio of pouch young was female-biased on both grids (range of 0.53-0.73). Isoodon obesulus were sexually dimorphic, with males being both heavier and larger than females. Only two juveniles were recruited to the populations over the entire three years of the study. Breeding among female I. obesulus was greatest in the December, low in the March, moderate in the September, and absent in the June trapping sessions. Mean litter size was 3.05 ± 0.26, with a range of 1-5 pouch young. For males and females, mean longevity for resident animals was 10.0 ± 3.7 and 13.5 ± 3.3 months, respectively. The mean home range area for the two resident males and the five resident females with ≥8 captures was 6.95 ± 1.95 and 3.28 ± 1.02 hectares, respectively. There was minimal overlap between the home ranges of individual I. obesulus.

Demography and home range of the eastern barred bandicoot (Perameles gunnii) in south-eastern Tasmania

2000 ◽  
Vol 27 (1) ◽  
pp. 103 ◽  
Author(s):  
Stephen A. Mallick ◽  
Michael M. Driessen ◽  
Gregory J. Hocking
Keyword(s):  
Body Weight ◽  
Sex Ratio ◽  
Home Range ◽  
Home Ranges ◽  
Sexually Dimorphic ◽  
South Eastern ◽  
Small Width ◽  
Live Trapping ◽  
Dry Conditions ◽  
Two Populations

We used live-trapping to study the demography and movement of two populations of the eastern barred bandicoot, Perameles gunnii, in south-eastern Tasmania from 1992 to 1996. Densities were 0.35–2.35 animals ha–1. Sex ratios were male-dominated on Grid I and female-dominated on Grid II. The average body weight for sexual maturity was 700g for males and 680g for females, while the lowest recorded weight for a breeding female was 570g. Perameles gunnii was sexually dimorphic, with males having a greater body weight and pes length than females. Recruitment was 25.4–32.1%, residence 46.7–100.0%, and emigration 16.5–25.5% of the population. Three juveniles were recruited to the Grid I population, 55 to Grid II, with a steady decline in the number of juveniles recruited to Grid II over the four years of the study. Breeding occurred year-round. Mean litter size was 2.53, with 78.2% of all litters having either 2 or 3 young. Mean longevity for male and female P. gunnii was 7.91 and 10.54 months, respectively. Home ranges of males (4.29 ha) were significantly larger than those of females (2.34 ha), although this may represent a significant underestimate due to the small width of our grids (200m) relative to the home-range area. There was only moderate overlap (19.3%) between home ranges of males and females. The overlap between male/male home ranges (4.4%) was significantly less than the overlap between female/female home ranges (15.8%). Perameles gunnii carried both ticks and fleas, with flea infestation being significantly higher on Grid I than on Grid II. Both populations underwent a significant decline over the study period, apparently the result of the unusually dry conditions over the first 3 years of the study. A deterioration in conditions was associated with a steady loss of resident adults, declining recruitment of juveniles and an increase in the male/female sex ratio. The sex ratio of P. gunnii populations may provide a convenient index of habitat quality, with poor or deteriorating conditions apparently associated with a high or increasing numbers of males to females.

Population parameters of ringed seals (Phoca hispida Schreber, 1775) in the Svalbard area

1987 ◽  
Vol 65 (4) ◽  
pp. 1021-1027 ◽  
Author(s):  
Christian Lydersen ◽  
Ian Gjertz
Keyword(s):  
Sex Ratio ◽  
Ringed Seal ◽  
Adult Males ◽  
Population Parameters ◽  
Phoca Hispida ◽  
Age Class ◽  
Ringed Seals ◽  
Males And Females ◽  
The Mean ◽  
Sexually Mature

Samples were taken from 284 ringed seals (Phoca hispida) in the Svalbard area during April–July 1981 and March–April 1982. The age of 283 seals was determined by reading annuli in the cementum of the canine teeth. The mean age of the males was 11.3 years, and of the females, 14.9 years. Females were found to be significantly older than males. The mean length of sexually mature ringed seals was 128.9 cm for both sexes. The mean weight of adult males and females was 53.5 and 61.4 kg, respectively. Females were found to be significantly heavier than males. The sex ratio was 47.8% males and 52.2% females. Studies of microscopic sections of testis and epididymis from ringed seal males showed that 63, 75, and 80% of 5-, 6-, and 7-year-old animals, respectively, were sexually mature. The weights of testis and epididymis, diameters of tubuli, and the size of testis all showed a marked increase in the 5-year age-class. Macroscopic sections of ovaries from ringed seal females showed that 20, 60, and 80% of 3-, 4-, and 5-year-old animals, respectively, were sexually mature. The size of the ovaries showed a marked increase in the 5-year age-class. The ovulation rate of ringed seals from Svalbard was calculated to be 0.91.

Panulirus echinatus population in the Brazilian oceanic ecosystem Rocas Atoll

Crustaceana ◽  
2019 ◽  
Vol 92 (2) ◽  
pp. 221-232 ◽  
Author(s):  
Juliana Gaeta ◽  
Raúl Cruz
Keyword(s):  
Sex Ratio ◽  
Carapace Length ◽  
Reproduction Period ◽  
Males And Females ◽  
The Mean ◽  
Oceanic Ecosystem ◽  
Abundant Population ◽  
Future Information

Abstract In Rocas Atoll (03°51′S 033°48′W) a most abundant population of Panulirus echinatus Smith, 1869 was observed during free dives. Numbers of males and females were almost the same, with an overall sex ratio M : F = 1.1. In addition, males are larger than females, with a mean male carapace length (CL) of 92.6 ± 1.8 mm, while the female mean CL was 72.7 ± 1.0 mm and for both sex combined the mean CL was 83.1 ± 1.4 mm. The percentage of females breeding, i.e., with a spermatophore mass or eggs, was 75.1%. More information is needed to better understand the fluctuation in densities over a year cycle, the reproduction period, and differences in CL between males and females, as well as other aspects of the biology of this species. The present work and future information could help to formulate fisheries policies aimed at protecting P. echinatus stocks.

Movements, Activity Patterns and Habitat Use of Feral Pigs (Sus scrofa) in a Tropical Habitat

1997 ◽  
Vol 24 (1) ◽  
pp. 77 ◽  
Author(s):  
Peter Caley
Keyword(s):  
Habitat Use ◽  
Riparian Vegetation ◽  
Radio Telemetry ◽  
Activity Patterns ◽  
Early Morning ◽  
Home Range Size ◽  
Home Ranges ◽  
Feral Pigs ◽  
Live Trapping ◽  
The Mean

Movements, activity patterns and habitat use of feral pigs were studied in a tropical woodland habitat by radio-telemetry, live-trapping and hunter returns. The mean aggregate home-range size was 33.5 km2 for boars and 24.1 km2 for sows. Feral pigs were rather sedentary, with no tendency to disperse great distances from their initial home ranges. Pigs were most active at night, with peaks of activity in the late afternoon and early morning. Pigs preferentially used the riparian vegetation strip bordering major rivers, and grain crops, when available. The implications for the management of pigs are discussed.

scholarly journals A radio tracking study of home range and movements of the marsupial Micoureus demerarae (Thomas) (Mammalia, Didelphidae) in the Atlantic forest of south-eastern Brazil

2005 ◽  
Vol 22 (1) ◽  
pp. 85-91 ◽  
Author(s):  
Edsel Amorim Moraes Junior ◽  
Adriano Garcia Chiarello
Keyword(s):  
Home Range ◽  
Convex Polygon ◽  
Home Ranges ◽  
Radio Tracking ◽  
Minimum Convex Polygon ◽  
South Eastern ◽  
Live Trapping ◽  
Eastern Brazil ◽  
Data Points ◽  
Biological Reserve

From August 2001 to July 2002 the home range and movements of seven Micoureus demerarae (Thomas, 1905) (three males and four females) were investigated using radio tracking in the União Biological Reserve, state of Rio de Janeiro, south-eastern Brazil. A total of 436 locations was obtained and home range estimated with fixed Kernel (95% of data points), and minimum convex polygon (MCP) methods, with 100 and 95% of data points. Male home ranges estimated by MCP (100%) ranged from 5.4-24.2 ha and females from 0.3-10.7 ha. Corresponding figures calculated with Kernel (95%) were 4-10.9 ha for males and 1.3-5.9 ha for females. Animals travelled on average 423 m/night, with males travelling significantly further (582.8 m/night) than females (335.1 m/night) (t test, t = 3.609, p = 0.001). We concluded that radio tracking produced much larger home ranges than those estimated with traditional live-trapping techniques, suggesting that the latter might underestimate ranging when the area covered with traps is relatively small (ca. 1 ha or less). Radio tracking also indicated that M. demerarae, although predominantly arboreal and weighting only ca. 130 g., has movements similar in magnitude to larger-sized terrestrial didelphimorph marsupials, such as Didelphis Linnaeus, 1758, Philander Linnaeus, 1758 and Metachirus (Desmarest, 1817).

scholarly journals Are hermaphrodites better adapted to the colonization process in trioecious populations of Salix myrsinifolia?

2015 ◽  
Vol 84 (2) ◽  
pp. 167-175 ◽  
Author(s):  
Paweł Mirski ◽  
Emilia Brzosko
Keyword(s):  
Sex Ratio ◽  
Reproductive Number ◽  
Vegetative Traits ◽  
Average Share ◽  
Northeastern Poland ◽  
Colonization Process ◽  
Males And Females ◽  
Salix Myrsinifolia ◽  
Two Populations

In trioecious plant populations, the role of hermaphroditism is often uncertain. We investigated the advantages of hermaphroditism in the dioecious shrub <em>Salix myrsinifolia</em>. The sex ratio of 30 <em>S. myrsinifolia</em> populations in northeastern Poland (secondary range) and Lithuania (primary range) was investigated in 2010–2011. Measures of reproductive (number of catkins, number of flowers in catkins) and vegetative traits (height, diameter, number of shoots, vitality) were taken and compared among sexual morphs. In two populations, measurements collected 14 years prior on marked individuals were used to determine the rate of changes in height, crown diameter and survivorship rates. We found trioecy mostly in the secondary part of the range with an average share of hermaphrodites reaching 21% in the trioecious populations. The sex ratio varied between populations, but tended mostly towards female domination. Several traits differed significantly among sexes. The characteristics of hermaphrodites were often intermediate between males and females and provided no evidence for the higher competitive abilities of hermaphrodites. We concluded that the possible gain of hermaphroditism in the colonization process is restricted to reproduction. We consider hermaphroditism in <em>S. myrsinifolia</em> as an equilibrium between the allocation of resources for growth and reproduction in unstable conditions on the margins of the range.

Home Range and Movement Patterns of Sminthopsis leucopus (Marsupialia: Dasyuridae) In Coastal Dry Heathland, Anglesea, Victoria.

1996 ◽  
Vol 19 (1) ◽  
pp. 1
Author(s):  
S. Laidlaw W ◽  
S. Hutchings ◽  
R. Newell G
Keyword(s):  
Home Range ◽  
Average Distance ◽  
Home Range Size ◽  
Home Ranges ◽  
Eastern Australia ◽  
The Hours ◽  
Males And Females ◽  
The Mean ◽  
High Degree ◽  
Degree Of Overlap

Sminthopsis leucopus is a small dasyurid distributed in south-eastern Australia. Radiotelemetry in conjunction with live capture trapping was used to investigate home range size and habitat utilisation of S. leucopus. The average distance moved showed no significant differences between sexes or between seasons. The observed range length and home range area were similar for both sexes. The mean home range area (95% harmonic mean) for S. leucopus was 0.917 hectares. Home ranges of males and females revealed a high degree of overlap. Activity during the day was low and highest in the hours following dusk.

Infestation of ectoparasites in Gudusia chapra (Hamilton)

1970 ◽  
Vol 25 ◽  
pp. 23-25 ◽  
Author(s):  
Hamida Khanum ◽  
Haroon Or Rashid Khan ◽  
Rimi Farhana
Keyword(s):  
Sex Ratio ◽  
Key Words ◽  
Infection Rate ◽  
Monthly Basis ◽  
Female Sex ◽  
Infestation Intensity ◽  
Males And Females ◽  
The Mean

One hundred Gudusia chapra ranging from 6 to 17 cm were examined on monthly basis. Of 100 fishes, 32 were male and 68 were female, sex ratio being 1:2.1. A total of 163 parasites were recovered from the host, which 70% were trematodes and 16% copepods. The overall prevalence of infection was 86% and the mean±SD intensity was 1.89±0.91. Heavy infestations (100%) were recorded in males of the largest (14.25-17.0 cm) and the smallest (6.0-8.75 cm) length groups. Total infection rate was also higher in males (87.72%) than in females (83.82%). Intensity of infestation in males and females was 1.62 and 2.03, respectively. Key words: Gudusia chapra, ectoparasites, trematode, copepod, infestation intensity Univ. j. zool. Rajshahi Univ. Vol.25 2006 p.23-25

Bror Hanson's 'About Hepialus hecta' (1938): a pioneering study of moth behaviour (Lepidoptera, Hepialidae)

2018 ◽  
Vol 69 (3) ◽  
pp. 210-222
Author(s):  
John R. G. Turner
Keyword(s):  
Sex Ratio ◽  
Mating Behaviour ◽  
Courtship Behaviour ◽  
South Eastern ◽  
Males And Females ◽  
Made In

Hanson's (1938) atmospheric narrative of the mating behaviour of Phymatopus hecta is reprinted in a new translation from the Swedish. The paper is a classic of focussed investigation within a century in which only fragmentary information about this species was published; regrettably it remained unnoticed for forty years. Hanson established that the courtship behaviour was non-stereotypic (each of his three observed courtships was unique), and that both males and females could attract each other. He suggested that the males were deploying a pheromone, noted an extraordinary back to front copulation procedure, and was the first to report predation by wasps. All of which waited from half to three-quarters of a century before being reconfirmed. Some of his detailed observations are ambivalent, being at variance with recent observations in Scotland, suggesting either that the populations have diverged, or that the behaviour was locally modified because of a highly distorted sex ratio. Or he may simply have been inaccurate in distinguishing males from females. The reported timing of events suggests, using the time of sunset, that the observations were made in the region of Kalmar and Öland in south-eastern Sweden; there is a strong suggestion that the period of activity is shifted to a time more in advance of sunset, relative to the Scottish populations.

scholarly journals Demography of the enigmatic low phase in a cyclic lemming population

2021 ◽  
Author(s):  
Dominique Fauteux ◽  
Gilles Gauthier
Keyword(s):  
Sex Ratio ◽  
Reproductive Potential ◽  
Indirect Evidence ◽  
Adult Males ◽  
Density Dependent ◽  
Live Trapping ◽  
Biased Sex Ratio ◽  
Males And Females ◽  
Cyclic Populations

Abstract Deciphering the mechanism behind the lack of growth during the prolonged low abundance phase of cyclic populations represents a major challenge due to the lack of data. However, long-term capture-mark-recapture datasets can help resolve this question through demographic analyses. We analysed the demography and movements of cyclic brown lemmings on Bylot Island, Canada, with a 16-yr (2004-2019) live-trapping program and looked for inversely density-dependent factors that could contribute to a prolonged low phase. We found that the proportion of females in the population was inversely density-dependent with a strong male-biased sex ratio at low densities but not at high densities. In contrast, survival of adult females was higher than adult males, but both had lower survival at low densities than at high ones. Distances moved by both adult males and females were density-dependent, and proportion of females in reproductive condition was weakly density-dependent. Individual body condition, measured as monthly change in body mass, was not density-dependent. Overall, the strong malebiased sex ratio at very low densities suggests a loss of reproductive potential due to the rarity of females and appears to be the most susceptible demographic factor that could contribute to the prolonged low phase in cyclic brown lemmings. What leads to this sexbias in the first place is still unclear, but indirect evidence suggests that this may be due to a higher vulnerability of nesting females to predation in winter than males.

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