Notes on Reproduction and Growth in the Koala, Phascolarctos cinereus (Goldfuss)

1979 ◽  
Vol 6 (1) ◽  
pp. 5 ◽  
Author(s):  
M Smith
Keyword(s):  
Sex Ratio ◽  
Breeding Season ◽  
Growth Curves ◽  
Phascolarctos Cinereus ◽  
Old Females

Reproduction of koalas was studied at Lone Pine Koala Sanctuary, Brisbane, where 80% of births fall between October and January. Gestation ranges from 34 to 36 days. Females are monotocous. Those who wean their young in the first half of the breeding season breed again in the second half. Although polyoestrous, most females conceive at their first oestrus, except 2-y-olds. Males are mature at 3 y old, females at 2 y old. Young emerge from the pouch at 7 months, leave it completely at 9 months, and are weaned at approximately 12 months. Growth curves are provided. Those born early in the season grow faster than those born later; the age when growth ceases is unknown. Longevity is about 12y; and the sex ratio may be slightly biased towards females.

Biology of the Feral Cat, Felis Catus (L.), On Macquarie Island.

1985 ◽  
Vol 12 (3) ◽  
pp. 425 ◽  
Author(s):  
NP Brothers ◽  
IJ Skira ◽  
GR Copson
Keyword(s):  
Sex Ratio ◽  
Breeding Season ◽  
Felis Catus ◽  
Feral Cat ◽  
Feral Cats ◽  
Macquarie Island ◽  
Pregnant Females

246 feral cats were shot on Macquarie Island, Australia, between Dec. 1976 and Feb. 1981. The sex ratio ( males : females ) was 1:0.8. The percentages of animals with tabby, orange and black coats were 74, 26 and 2 resp. [sic]. Of the 64 orange cats, 56 were males . The breeding season was Oct.-Mar., with a peak in Nov.-Dec. The number of embryos in the 14 pregnant females averaged 4.7 (range = 1-9). The size of the 23 litters that were observed averaged 3 (range = 1-8). Kitten survival to 6 months of age was estimated to be <43%.

Effect of age and hunger on host-feeding behaviour by femaleTrichogramma euproctidis(Hymenoptera: Trichogrammatidae)

2013 ◽  
Vol 145 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Émilie Lessard ◽  
Guy Boivin
Keyword(s):  
Sex Ratio ◽  
Feeding Behaviour ◽  
Strategic Choice ◽  
Host Feeding ◽  
Feeding Frequency ◽  
Duration Distribution ◽  
Adult Parasitoid ◽  
Old Females ◽  
Effect Of Age

AbstractAdult parasitoid females can obtain proteins and lipid by consuming the haemolymph of their host. InTrichogrammaWestwood (Hymenoptera: Trichogrammatidae) species, host feeding on the host egg occurs after oviposition and leads to smaller offspring. We tested the effect of age and hunger on host-feeding behaviour of femaleTrichogramma euproctidisGirault. Young and old females, either starved, water fed, or honey fed, were observed and the host-feeding frequency, duration, distribution, and number of hosts used for nutrition were measured. The sex ratio (proportion of males) allocated to parasitised hosts where host feeding occurred and time taken to parasitise 10 hosts (indicator of female mobility) were also noted. The majority of females host fed on the first host encountered. Age had no impact on frequency, duration, number of hosts used, and mobility ofT. euproctidis. Starved females host fed longer and were less mobile. The sex ratio of the progeny emerging from the first host parasitised was more male biased when host feeding occurred. Host feeding had no effect on the sex ratio deposited elsewhere in the sequence of hosts encountered. Age of female had no effect on host feeding, possibly because host feeding incurs little cost for this species. To host feed on the first host parasitised, in which a male is allocated, is less costly in terms of fitness and represents a strategic choice for the female.

Reproductive Biology and Development of the Water Rat, Hydromys chrysogaster, in Captivity

1982 ◽  
Vol 9 (1) ◽  
pp. 39 ◽  
Author(s):  
PD Olsen
Keyword(s):  
Breeding Season ◽  
Developmental Stages ◽  
Post Partum ◽  
Growth Curves ◽  
Gestation Length ◽  
Body Measurements ◽  
Sperm Production ◽  
Crown Rump Length ◽  
Rate Of Increase ◽  
Hydromys Chrysogaster

In a captive colony of H. chrysogaster most litters were born between September and March, although some were born in every month except June. Most females had regular oestrous cycles in the breeding season but there were isolated instances of oestrus in every month. In mature males, testes were scrota1 and there was full sperm production all year. There was some regression in weight of male accessory reproductive glands in the autumn and winter. Oestrus lasted 10 days (range 7-17), and its stages: pro-oestrus 1 day, oestrus 2 days, metoestrus 2 days, anoestrus 5 days. Some instances of delayed implantation were suspected. Gestation length was 34 days (33-41). Parturition was followed the next day by a postpartum oestrus, lasting 1 day. Lactation anoestrus was at least 3 weeks. Litter size was 3.29 � 1.26 (1-7) and the number of litters per breeding season was 2.6 � 0.97 (1-5). In the latter half of pregnancy there was a linear relationship between the crown-rump length of foetuses and gestation length. Young were born naked, blind and with the pinnae folded forward with edges attached to the head. The upper incisors emerged at 4 days, the lower incisors at 6 days, the auditory meatus opened at about 10 days, the eyes opened at about 14 days, some solids were eaten and young were more independent at about 3 weeks of age, and they were weaned at about 29 days. Phases in the rate of increase in weight were associated with each of these developmental stages. Females were first capable of breeding at 124 days (433 g); most matured about 240 days in the season following that of their birth. The testes descended in males between 90 and 120 days (475 g) but full sperm production did not occur until about 130-140 days. Females could breed for three seasons (until about 3.5 y old). Placental scars were visible for up to 6 months, but had sometimes disappeared at 4 months post partum. Growth curves of tail and weight were sigmoid, and those of other body measurements were exponential, as in the Rattus group of Australian rodents, and differing from the pseudomyine rodents. Body measurements showed a sigmoid relationship to the linear equivalence of body weight. Developmental events occurred earlier, in relation to growth, in Hydromys and Rattus lutreolus than in Pseudomys novaehollandiae.

Catastrophic ongoing decline in Cambodia’s Bengal Florican Houbaropsis bengalensis population

2019 ◽  
Vol 30 (2) ◽  
pp. 308-322 ◽  
Author(s):  
SIMON P. MAHOOD ◽  
CHAMNAN HONG ◽  
SON VIRAK ◽  
PHEARUN SUM ◽  
STEPHEN T. GARNETT
Keyword(s):  
Sex Ratio ◽  
East Asia ◽  
Breeding Season ◽  
Total Population ◽  
East Asian ◽  
South East Asia ◽  
Conservation Area ◽  
Conservation Programme ◽  
Tonle Sap ◽  
Rate Of Decline

SummaryIn 2013 a prediction was made that the South-East Asian subspecies of Bengal Florican Houbaropsis bengalensis blandini would be extinct within 10 years. In 2018 we conducted a survey in the Tonle Sap floodplain, Cambodia, of the last population of Bengal Florican in South-East Asia. We found that the rate of decline in displaying males was 55% over five years, a decline comparable to that recorded between 2005–2007 and 2012. The estimated number of displaying males in 2018 was 104 (95% CI: 89–117), down from 216 (156–275) in 2012. We also conducted surveys by flushing birds in the non-breeding season, which indicated that the sex ratio of males to females is 3:1. We therefore estimate that the total population of adult Bengal Floricans in Cambodia in 2018 was 138 (119–156), making H. b. blandini the most threatened bustard taxon. The number of sites that support displaying male Bengal Floricans was reduced from 10 to four between 2012 and 2018. Between 2012 and 2018 we monitored numbers of displaying males in most years at the sites that support 80% of the total population. The only site where numbers of birds are stable is Stoung-Chikraeng Bengal Florican Conservation Area, where there were 44 (25–63) displaying males in 2018. This is the only site that has an ongoing NGO-government conservation programme. Our data indicate that Bengal Floricans are lost from sites when the area of grassland falls below 25 km2. We found evidence that displaying male Bengal Floricans abandon display territories when grassland is lost, this also creates hope that they may disperse and could colonise newly created habitat. All remaining sites that support Bengal Floricans in Cambodia are imperilled and we outline what must be done to reduce the possibility that H. b. blandini will be extinct by 2023.

IRRADIATION OF SPERM AND OOCYTES IN ONCOPELTUS FASCIATUS (HEMIPTERA: LYGAEIDAE): SEX RATIO, FERTILITY, AND CHROMOSOME ABERRATIONS IN THE F1 PROGENY

1973 ◽  
Vol 15 (4) ◽  
pp. 713-721 ◽  
Author(s):  
L. E. LaChance ◽  
R. D. Richard
Keyword(s):  
Sex Ratio ◽  
Gamma Irradiation ◽  
Chromosome Aberrations ◽  
Oncopeltus Fasciatus ◽  
X Rays ◽  
Virtual Absence ◽  
Chromosome Translocations ◽  
F1 Progeny ◽  
Old Females

Adult Oncopeltus fasciatus were irradiated as 7- to 8-day-old males, and as 3- to 4- or 10- to 12-day-old females with doses of 8 and 20 krad of gamma irradiation and 200 R of X-rays, respectively. Treated bugs were outcrossed to untreated bugs, and F1 progeny derived from irradiated sperm and from prophase and metaphase oocytes were studied. All treated bugs were less fertile than the controls, but none of the treatments produced full sterility. Among the F1 generation from the three types of crosses, there was no significant deviation from a 50:50 sex ratio.When F1 males were outcrossed to untreated females, only the males derived from irradiated sperm were semisterile; F1 males derived from the treated oocytes were as fertile as the controls. The semisterility of the F1 males was correlated with chromosome translocations and fragments in the spermatocytes. The virtual absence of these aberrations in the testes of F1 males derived from irradiated oocytes suggests that these aberrations are not induced in oocytes, are repaired, or are not included in the maternal pronucleus after irradiation of meiotic oocytes.

Behaviour of the Koala, Phascolarctos cinereus (Goldfuss), in Captivity VI*. Aggression

1980 ◽  
Vol 7 (2) ◽  
pp. 177 ◽  
Author(s):  
M Smith
Keyword(s):  
Breeding Season ◽  
Aggressive Behaviour ◽  
Motor Pattern ◽  
Dominance Hierarchies ◽  
Phascolarctos Cinereus ◽  
Aggressive Interactions ◽  
Single Motor ◽  
Low Level ◽  
In Captivity

'In a colony of captive koalas, all aggressive behaviour was a variation on the single motor pattern of throwing a foreleg around an opponent and biting. Squabbles (the most common aggressive behaviour) were brief, low level interactions usually arising from the efforts of one koala to climb past or over another. Minor fghts involved only single bites and the combatants stayed in the same place; major ,fights involved multiple bites and changes of position. Dependent young were seldom involved in aggression. Between males. minor fights were essentially intensified squabbles, but major fights involved wrestling and chasing; they were more likely between males unfamiliar with each other, or those already aroused by, e.g., other aggressive interactions. Females became aggressive especially during pregnancy and at the end of lactation. At such times they stood their ground and vocalized at other koalas, especially males, but attacked only if the opponent came within reach. Although the opponent usually withdrew. sometimes a male seemed provoked to attack. Males sometimes attacked females without obvious provocation. Aggression was slightly more common in than outside the breeding season. Competition for females or food, dominance hierarchies, appeasement, and the defence of young were not seen.

Studies on the behaviour on the South Ausralian fur seal, Arctocephalus forsteri (Lesson) II. Adult females and pups

1971 ◽  
Vol 19 (3) ◽  
pp. 267 ◽  
Author(s):  
I Stirling
Keyword(s):  
Sex Ratio ◽  
Breeding Season ◽  
Male And Female ◽  
Specific Location ◽  
Adult Females ◽  
Specific Behaviour ◽  
Fur Seal ◽  
O 47 ◽  
High Degree ◽  
Regular Patterns

A. forsteri pups were all weaned by 1 year old and were then totally absent from the island during the breeding season. The recorded intervals, for three tagged females, between apparent weaning of one pup and birth of the next were 29, 40, and 60 days. Some females became infested with barnacles during the period of feeding at sea prior to parturition. Adult females showed a high degree of fidelity to specific breeding colonies. Little specific behaviour, other than restlessness, preceded birth. Five observed births took from 5 sec to 4 min. Pups could swim when born. Male and female newborn pups weighed 4.41 =0.60 and 4.11 +O.47 kg respectively; the sex ratio was not significantly different from unity. Pups stayed with their mothers at a specific location for the first few days, after which the females began to feed at sea and the pups began to associate with each other. Females had not established regular patterns of presence and absence in the pupping colony by early February, but did so by late April. Females did not defend even newborn pups from approaching humans.

Long-term survival, length of breeding season, and operational sex ratio in a boreal population of common frogs, Rana temporaria L.

1990 ◽  
Vol 68 (1) ◽  
pp. 121-127 ◽  
Author(s):  
Johan Elmberg
Keyword(s):  
Sex Ratio ◽  
Breeding Season ◽  
Rana Temporaria ◽  
Return Rate ◽  
Operational Sex Ratio ◽  
Adult Males ◽  
Term Survival ◽  
Size Dependent ◽  
Survival Selection

A population of individually marked adult Rana temporaria was studied during the breeding season in 1979–1988 in east-central Sweden. Annual return rate averaged 31% (range 16–51%) in males and 16% (range 5–33%) in females. Return rate was not size dependent but increased with every successful previous hibernation, indicating an increased survival rate with age. Return rate was not correlated with winter harshness. Once adult, males had on average 1.5 (maximum 6) seasons with the possibility of reproducing. Corresponding values for females were 1.4 and 4. Mean length of the breeding season was 20 (SD = 2) days. Calling generally started at water temperatures below 3 °C. The lowest spawning temperature was 1 °C. Average temperatures at spawning onset and peak spawning were 5 and 6 °C, respectively. Large males tended to arrive earlier at the pond than small males. Males arrived earlier and stayed longer than did females. The overall population sex ratio was close to unity. The operational sex ratio (OSR) varied during the breeding season, averaging 0.54 (one female to two males). No male was observed to mate more than once per season. I argue that survival selection is more important to male lifetime mating success than is competition in the breeding pond (sexual selection as affected by OSR and length of the breeding season).

Facultative sex allocation in the viviparous lizard Eulamprus tympanum, a species with temperature-dependent sex determination

2003 ◽  
Vol 51 (4) ◽  
pp. 367 ◽  
Author(s):  
Kylie A. Robert ◽  
Michael B. Thompson ◽  
Frank Seebacher
Keyword(s):  
Sex Ratio ◽  
Sex Determination ◽  
Breeding Season ◽  
Sex Allocation ◽  
Adult Population ◽  
Selective Advantage ◽  
Adult Males ◽  
Temperature Dependent ◽  
Maternal Manipulation

Females of the Australian scincid lizard Eulamprus tympanum can manipulate the sex of their offspring in response to gender imbalances in the population using temperature-dependent sex determination. Here we show that when adult males are scarce females produced male-biased litters and when adult males were common females produced female-biased litters. The cues used by a female to assess the adult population are not known but presumably depend upon her experience throughout the breeding season. Maternal manipulation of the sex ratio of the offspring in E. tympanum illustrates a selective advantage of temperature-dependent sex determination in a viviparous species.

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