Research Article
Reproductive behaviour and food consumption associated with the captive breeding of platypus (Ornithorhynchus anatinus)
- Norm Holland, Stephen M. Jackson
-
- Published online by Cambridge University Press:
- 14 February 2002, pp. 279-288
-
- Article
- Export citation
-
A female platypus Ornithorhynchus anatinus was intensively monitored with the use of video equipment in captivity at Healesville Sanctuary, Victoria, Australia to record feeding and behavioural changes that occurred as a result of only the second successful raising of young platypus (twins) in captivity. These results revealed the female to be inactive (not leaving the burrow) for periods up to 6 days, and mating occurred 15–21 days before eggs were laid. The nest was built over 5 nights between 5 and 9 days before the eggs were laid. The eggs were thought to have been laid during a 4-day period when the female was confined to her burrow. Once the eggs were laid there was a slow initial rate of feeding which sharply rose 20 days after the eggs were laid. The first time the female spent a day away from the young was 39 days after the eggs were laid, after which she decreasingly nested with them until she spent only 8% of the time with them when they emerged from the burrow, 131 and 136 days after the eggs are thought to have been laid. She rarely went in the nest after day 155, suggesting that the lactation period is c. 135–145 days, assuming 10 days for incubation. The time of emergence also corresponded with the peak in the female''s food consumption, which correlates well with the high demands of late lactation, with the daily food intake reaching c. 90–100% of body weight 140 days after the eggs are thought to have hatched. This captive breeding of the platypus has provided the first records of the gestation period, food consumption in relation to breeding stage, the time the female spends with her young during their development, and a partial growth curve of developing platypus.
The relationship between foot size of wild canids and regional snow conditions: evidence for selection against a high footload?
- D. L. Muray, S. Larivière
-
- Published online by Cambridge University Press:
- 14 February 2002, pp. 289-299
-
- Article
- Export citation
-
Mammals occupying northern areas may experience reduced fitness through the deleterious effects of snow on locomotion, energy expenditure, and food acquisition. Accordingly, in areas of deep and soft snow, selection may favour mammals possessing disproportionally large feet and lower footload (body mass/foot surface area). We collected carcasses of coyote Canis latrans (n = 472), red fox Vulpes vulpes (n = 199), arctic fox Alopex lagopus (n = 52), grey fox Urocyon cinereoargenteus (n = 17), and wolf Canis lupus (n = 14) and compared body mass, total foot area, difference in surface area between front and hind feet, and footload, among species and populations. All measured morphological attributes differed significantly among canid species; grey fox had the smallest feet, whereas arctic fox had both the lightest mass and lowest footload of all canids. For all species, adult males tended to be heavier and have larger feet than did adult females, and for most species adults were heavier and larger than were juveniles. Foot area in red foxes increased significantly with latitude, with populations found north of 48 °N (i.e. approximate latitude where snow may become limiting) averaging 12% larger feet than those found farther south. For coyotes, body mass increased with latitude, with populations found north of 48 °N averaging 26% heavier mass than those occurring farther south. Coyote foot area also increased with latitude, with populations found north of 48 °N averaging 25% larger feet than those found farther south. When indices of snow severity (mean annual snowfall, mean number of days with snowcover) were considered, foot area for red foxes was correlated with annual snowfall as well as latitude, whereas coyote morphology failed to correlate with any snow-related variables. These results suggest that snow may have contributed to selection for foot size in some wild canids (i.e. arctic fox, red fox), but such selective forces were probably relatively weak and inconsistent across species.
Gonadal development and mode of sexuality in a coral-reef damselfish, Dascyllus trimaculatus
- Kazue Asoh, Maiko Kasuya
-
- Published online by Cambridge University Press:
- 14 February 2002, pp. 301-309
-
- Article
- Export citation
-
The process of early gonadal development and the mode of sexuality were examined in the three-spot damselfish Dascyllus trimaculatus. All gonads developed an ovarian lumen and primary-growth-stage oocytes after an initially undifferentiated state. From this ovarian state or from more developed ovaries, some gonads redifferentiated into testes. None of 130 individuals examined had a gonad containing degenerating vitellogenic oocytes and proliferating spermatogenic tissue. Nineteen individuals, however, had a gonad containing degenerating cortical–alveolus stage oocytes and proliferating spermatogenic tissue. The size of these individuals overlapped with the female size range in which most females were still in the middle of the maturation process or the smallest female size class in which most females had vitellogenic oocytes. This suggests that the transition toward maleness in these individuals is likely to have occurred after oocytes in their gonads attained cortical–alveolus stage, but before their final maturation and spawning as females, and that the protogynous pattern of gonadal development in D. trimaculatus is non-functional. The observed protogynous pattern seems to have been present in the common ancestor of the genus and have been retained in this descendant species.
Asymmetrical gaits of juvenile Crocodylus johnstoni, galloping Australian crocodiles
- S. Renous, J.-P. Gasc, V. L. Bels, R. Wicker
-
- Published online by Cambridge University Press:
- 14 February 2002, pp. 311-325
-
- Article
- Export citation
-
Seven juvenile individuals of the Australian species Crocodylus johnstoni from the Frankfurt Zoological Park were filmed on high-speed video, at 250 fields s−1, whilst freely moving at various speeds in a long corridor. The sequences of locomotion were analysed to determine the various space and time parameters to characterize limb kinematics. We found that the animals use diverse patterns of asymmetrical gait, revealing great flexibility in limb co-ordination. In all these gaits, the forelimb strikes the ground first, in the couple made by diagonally opposite fore- and hindlimbs. Among these gaits, rotary gallop offers probably a high level of manoeuvrability, whereas transverse gallop resulted in a higher level of stability. Speed increase is achieved by half-bound and bound, the latter being the only gait used at velocities > 2 m s−1. Speed was increased mainly by increasing the stride length of the fore- and hindlimbs by simultaneously increasing both its components, the step and swing lengths. However, in bound, the step length of each forelimb increased more than the swing length, resulting in a stronger thrust action, whereas swing length increased more than step length for the hindlimb, causing the centre of mass to accelerate forwards during its ballistic phase. The asymmetrical gaits of crocodiles such as Crocodylus johnstoni are probably not functionally equivalent to the transitional asymmetrical gaits exhibited by lizards when building up into a bipedal run. These gaits are also not entirely equivalent to mammalian gaits, despite the use of vertical movements of the vertebral axis in these crocodiles, favouring an erect dynamic posture.
Patterns of species richness and narrow endemism of terrestrial bird species in the Afrotropical region
- Helen M. de Klerk, Tim M. Crowe, Jon Fjeldså, Neil D. Burgess
-
- Published online by Cambridge University Press:
- 14 February 2002, pp. 327-342
-
- Article
- Export citation
-
Geographical patterns and peaks of species richness and narrow endemism (defined by range-restrictedness and range-size rarity) are described for terrestrial Afrotropical birds and subsets thereof based on residency, endemism, and taxonomy. Species richness for residents and Afrotropical endemics (species globally restricted to sub-Saharan Africa) peaks along the mountains and adjacent lowlands of eastern and southern Africa. Isolated mountains in central and western Africa and the lowlands of the north-eastern Congo Basin (Ituri) are highlighted to a lesser degree. Peaks of narrow endemism occur in these areas as well as in the Ethiopian Highlands (particularly for non-passerines), Somalia (particularly for passerines), and the Angolan Escarpment. Within residents, patterns of species richness vary greatly between Afrotropical endemics (which concentrate in forests on mountains and adjacent lowlands, and the southern Brachystegia woodlands) and non-endemic residents (which concentrate in Sudanian woodlands and the Ethiopian Highlands). Patterns of species richness of residents (species that breed in the Afrotropics) and non-breeding migrants (non-breeding visitors to the Afrotropics) also show notable differences. The latter concentrate in areas close to the Palaearctic, which forms their distributional range centres. Patterns of species richness and narrow endemism for Afrotropical endemics show broad-scale coincidence within mountains or mountain–lowland complexes, particularly the Cameroon–Bamenda Highland system, East African rift system and Eastern Arc mountains. However, fine-scale coincidence of peaks of species richness and narrow endemism within these complexes is low. Narrow endemism peaks occur in areas of topographical complexity, which may have conferred localized climatic stability over short-, medium-, and long-term climatic cycles (sensu Fjeldså, 1994; Fjeldså et al., 1997), allowing these areas to act as ‘species pumps’. Species accumulate in areas of high productivity. Lack of fine-scale coincidence of narrow endemism and species richness peaks have implications for conservation prioritization exercises.
Postnatal growth in body length and mass of polar bears (Ursus maritimus) at Svalbard
- A. E. Derocher, Ø. Wiig
-
- Published online by Cambridge University Press:
- 14 February 2002, pp. 343-349
-
- Article
- Export citation
-
The von Bertalanffy curve was used to examine growth patterns in both body length and mass of female and male polar bears Ursus maritimus live-captured near Svalbard, Norway. A longer growth period in males resulted in pronounced sexual dimorphism in both body length and mass. Males were 1.16 times longer and 2.10 times heavier than females. The asymptotic body length of female and male polar bears from Svalbard was smaller than that for polar bears in four of six previously studied populations. Asymptotic body mass of females from Svalbard was lower than other previously studied populations, while males were generally lighter. The reasons for the lighter bears in Svalbard are unclear, but we believe they were not related to sampling error, ecosystem productivity, or genetic differences. The high pollution load of polar bears in Svalbard may have affected body size but this potential factor could not be assessed. The generally smaller size of polar bears in Svalbard was consistent with density-dependent growth effects but again, information on population density relative to carrying capacity was insufficient to assess this hypothesis.
Milk consumption, body composition and pre-weaning growth rates of Australian fur seal (Arctocephalus pusillus doriferus) pups
- John P. Y. Arnould, Mark A. Hindell
-
- Published online by Cambridge University Press:
- 14 February 2002, pp. 351-359
-
- Article
- Export citation
-
Pre-weaning growth rates, body composition, milk consumption and mass gain efficiency were measured in Australian fur seal Arctocephalus pusillus doriferus pups born in two consecutive breeding periods. Australian fur seals have the highest birth mass of any fur seal species (male 8.3 kg; female 7.2 kg). While their absolute pre-weaning growth rate (male 62 g·day−1; female 53 g·day−1) is similar to that of other temperate latitude fur seals, they have the longest birth-mass doubling time of any otariid species (134–136 days). Daily milk consumption increased from 400 g·day−1 (5 MJ·day−1) after birth to 675 g·day−1 (13.7 MJ·day−1) at age 210 day. However, mean mass-specific milk consumption (41 g·kg−1) is substantially lower than in other otariid species (58–70 g·kg−1) and, combined with a low mass gain efficiency (0.12 g·g−1), contributes to the low mass-specific growth rates observed. There were no significant differences in either absolute or mass-specific milk consumption between the sexes. Significant differences, however, were found between the sexes in the body composition of pups with females generally having larger body lipid stores than males for any given mass. Peak milk yield by Australian fur seal females is estimated at 0.60 MJkg−0.75, substantially less than in Antarctic fur seals. The low level of maternal energy transfer in Australian fur seals may reflect the relatively low marine productivity of their foraging areas.
Mortality patterns of otters (Lutra lutra) from eastern Germany
- Silke Hauer, Hermann Ansorge, Olaf Zinke
-
- Published online by Cambridge University Press:
- 14 February 2002, pp. 361-368
-
- Article
- Export citation
-
Data obtained from the dissection of 1067 otters Lutra lutra were used to compare the causes of mortality in relation to age composition, time trends, and regions. Age determination was based on the analysis of incremental cementum lines in teeth. Major causes of mortality of otters were traffic accidents (69.9%), followed by natural deaths (6.6%), deaths in fish-traps (6%), hunting (4.1%), and other violent events (4.4%). No significant differences in mortality structure between the sexes were found. Resulting from a log-linear and a contrast analysis, significant differences in frequencies of mortality causes in relation to different time periods, regions and age classes of otters were observed. The frequency of otters dying from hunting or diseases was highest in youngest (AC I) and oldest (AC V) otters. Generally, the greatest differences between age classes resulted from comparison of frequencies of traffic-mortality, hunting, and fish-traps. Concerning time trends, the greatest differences were found in the periods before and after 1990. In addition to the increase of traffic-mortality, hunting and deaths in fish-traps influenced the distribution of mortality in different time periods. In eastern Germany, there is a clear difference in mortality between northern and southern regions. This results mainly from commercial fish-trapping being more common at the northern coast and lakes. However, in all different subsamples of time, region or age-class, traffic-killed otters amounted to >50% of all otters found dead.
Genetic evidence for the origin of the agrimi goat (Capra aegagrus cretica)
- Gila Kahila Bar-Gal, Patricia Smith, Eitan Tchernov, Charles Greenblatt, Pierre Ducos, Armelle Gardeisen, Liora Kolska Horwitz
-
- Published online by Cambridge University Press:
- 14 February 2002, pp. 369-377
-
- Article
- Export citation
-
The agrimi goat Capra aegagrus cretica is unique to Crete and its offshore islands. It has been identified as a sub-species of the wild bezoar goat Capra aegagrus aegagrus Erxleben, 1777, which it closely resembles in horn shape, body form and coloration. This classification has been disputed by some researchers who claim that the agrimi are feral goats, derived from early domestic stock brought to the island by the first Neolithic settlers. In order to clarify this issue, DNA analyses (cytochrome b and D loop sequences) were carried out on tissue of live and skeletonized agrimi and compared to sequences of wild and domestic caprines. Results conclusively show the agrimi to be a feral animal, that clades with domestic goats (Capra hircus) rather than with wild Asiatic bezoar. This study demonstrates that morphometric criteria do not necessarily reflect genetic affinities, and that the taxonomic classification of agrimi should be revised.
Capture success of little brown bats (Myotis lucifugus) feeding on mosquitoes
- Jens Rydell, Doreen Parker McNeill, Johan Eklöf
-
- Published online by Cambridge University Press:
- 14 February 2002, pp. 379-381
-
- Article
- Export citation
-
A small colony of little brown bats Myotis lucifugus was observed feeding on mosquitoes (Culicidae) inside a barn near Fairbanks, Alaska in June 2000. Observations were made visually and with a bat detector. All capture attempts were associated with feeding buzzes, indicating that the bats used echolocation to detect and track the insects, although the light was bright and the insects were easily seen by us. The capture efficiency of the bats was 92% (n = 100). The insects did not show any defensive behaviour in response to approaching bats.
Changes in climate and in the timing of pairing of the Australian lizard, Tiliqua rugosa: a 15-year study
- C. Michael Bull, Dale Burzacott
-
- Published online by Cambridge University Press:
- 14 February 2002, pp. 383-387
-
- Article
- Export citation
-
Over 15 years (1983–97) 25 665 random encounter captures of adult sleepy lizards, Tiliqua rugosa, were made at a site near Mt Mary, in the mid-north of South Australia. The last months of winter (July and August) became warmer and drier in the later years of the study, and the spring months when lizard activity was highest (September and October) had increased rainfall. The lizards form monogamous pairs for an average of 8 weeks before mating in late October or early November. Pairing started earlier and lasted longer in later years of the study. The time when pairing ended showed no significant temporal trend, although it was earlier in years with warmer spring temperatures. These results suggest that the timing of reproductive behaviour was influenced by climatic variation.
Female dispersal and relatedness structure in common wombats (Vombatus ursinus)
- Sam C. Banks, Lee F. Skerratt, Andrea C. Taylor
-
- Published online by Cambridge University Press:
- 14 February 2002, pp. 389-399
-
- Article
- Export citation
-
Dispersal patterns were investigated in the common wombat Vombatus ursinus using microsatellite genetic data collected from three study sites. Two of these were within large, high-density populations in Victoria, south-eastern Australia, while the third was a small, isolated population in South Australia. Genetic assignment tests revealed that in the continuous populations, females were more likely to be immigrants into the sampling areas than were males, who were more likely to have been born locally. No such difference between the sexes was detected for the isolated population. At all three sites, pairwise relatedness estimates for males were negatively correlated with geographic distance, suggesting related males were clustered. This pattern was not observed among females, other than in the isolated population, where pairs of females showed a weak decline of relatedness with increasing geographic distance over a large spatial scale. Taken together, these data provide strong evidence that dispersal is predominantly by females. Furthermore, the observed spatial structure of relatedness suggests female breeding dispersal, a rare finding among mammalian species. Genetic variation within the isolated population was significantly reduced compared to the sites in Victoria. Our data are not sufficient to distinguish between two possible causes for this: (1) long-term small size and isolation of populations at the edge of the species' range where resources may be more patchily distributed; (2) a genetic bottleneck effect of recent isolation resulting from agricultural development.
Determinants of gregariousness in the spectral tarsier (Prosimian: Tarsius spectrum)
- Sharon Gursky
-
- Published online by Cambridge University Press:
- 14 February 2002, pp. 401-410
-
- Article
- Export citation
-
Interspecific comparisons of mammals and primates suggest that the major determinants of gregarious behaviour are the distribution of food resources in space and time, predation pressure and infanticide avoidance. This study of gregarious behaviour in the spectral tarsier Tarsius spectrum at Tangkoko Nature Reserve, Sulawesi Indonesia suggests that all three may be important in understanding the relatively gregarious nature of spectral tarsiers. To test whether predation pressure was the major determinant of sociality for this species, I mimicked predation pressure by using predator models and playback predator vocalizations. In response to increased predation pressure from rubber models of snakes, the family group was observed mobbing the ‘predator’. On the other hand, when plastic bird of prey models were placed throughout the tarsier's territory the adult group members often increased their distance from one another. No significant response was made by the spectral tarsiers in response to playbacks of predator vocalizations. To test whether infanticide avoidance was the major determinant of sociality for this species, I compared the distance between adult males and females for three reproductive phases. When adult females were lactating, adult males were observed to decrease the distance between themselves and the adult female, while the female often attempted to increase the distance. However, groups containing either a pregnant female or a non-reproductive (cycling) female did not differ in their gregariousness. To explore whether the temporal distribution of resources was the major determinant of sociality in spectral tarsiers I collected insects hourly. The diet of spectral tarsiers is restricted to insects. Distance between group members closely followed hourly and monthly changes in insect abundance. During hours when abundance was high, distance between group members decreased and vice versa. Additional long-term and more fine-grained data need to be collected to ascertain the relative importance of resources, predators and infanticide in determining sociality in the spectral tarsier.
Prey abundance and food habit of tigers (Panthera tigris tigris) in Pench National Park, Madhya Pradesh, India
- S. Biswas, K. Sankar
-
- Published online by Cambridge University Press:
- 14 February 2002, pp. 411-420
-
- Article
- Export citation
-
Food habits of tigers Panthera tigris and population attributes of prey species (population structure, density and biomass) were studied in the tropical dry deciduous forest of Pench National Park, Central India, from November 1998 to April 1999. Scat analysis and line transect method were used to estimate tiger food habits and density of major prey species, respectively. The 61.1 km2 intensive study area was found to have very high ungulate density (90.3 animals km−2) with chital Axis axis being the most common species (80.7 animals km−2), followed by sambar Cervus unicolor (6.1 animals km−2). Common langur Presbytis entellus was the most abundant (77.2 animals km−2) primate species. When the density figures were multiplied by the average weight of each prey species, a high biomass density of 6013.25 kg km−2 was obtained for the intensive study area. Chital (47.3%) along with sambar (14.5%) and wild pig Sus scrofa (10.9%) constituted the major part of the tiger's diet. If there is food choice, tigers seem to kill medium- and large-sized species more often. Wild pig and sambar were consumed more than their availability, whereas chital were taken in proportion to their availability. Gaur Bos gaurus and nilgai Bosephalus tragocamelus were not represented in the tiger's diet. Common langur was consumed in lesser proportion by tigers than expected by estimates of its density. The average weight of animals consumed by tigers in the intensive study area was 82.1 kg. The analyses revealed that Pench harbours very high prey density and tigers are mostly dependent on the wild ungulates rather than on domestic livestock as is the case in many other areas in the Indian subcontinent. These two factors thus make Pench National Park a potential area for long-term conservation of tigers.