GROWTH AND DISTRIBUTION OF A SOUTHERN ELEPHANT SEAL COLONY

In contrast with most southern elephant seal, Mirounga leonina , colonies, births at Península Valdes, Argentina, increased from 7,455 in 1982 to 9,636 in 1990. Colony size during the 1990 breeding season, including pups, was estimated at 19,000. Colony growth may respond to abundant food resources and lack of competitors. The range of distribution of elephant seals in Patagonia has not changed since at least 1972 but the spatial distribution of births along the coastline of Peninsula Valdes has varied. In 1982, 58% of the births occurred in the northeast portion of the Peninsula versus 36% in 1990. Females may prefer to give birth on broad, sandy beaches. In 1982, 56% of the females gave birth on pebble beaches and 44% on sandy beaches. In 1990, 24% bred on pebbles versus 76% on sand. Sand substrate may be preferred by females because it may confer thermoregulatory advantages in relieving heat stress.     

BREEDING BIOLOGY OF SOUTHERN ELEPHANT SEALS IN PATAGONIA

Abstract: Elephant seals breed in Patagonia (Península Valdés, Argentina) from late August to early November, reaching peak numbers during the first week in October. Observations of this population over the past ten years yielded similar results. Eighty percent of the pups were born by 2 October. Most (96%) of 663 females marked during three breeding seasons gave birth to a pup. Females stayed on land a mean of 28 d, gave birth 6 d after arrival, nursed their pups for 22 d, and copulated a mean of 2.5 times 20 d after parturition and 2 d before departure. Copulations peaked during the third week in October. Males spent 57–80 d on land fasting and defending harems of up to 134 females (median 11–13 females, depending on year). Most (96%) marked females that gave birth ( n = 636) also weaned their pups successfully. Pup sex ratio was unity. Harems were smaller and breeding occurred about three weeks earlier in Patagonia than in other colonies. Thermal conditions, day length and food availability may explain clines in the timing of breeding events between populations, Other parameters of the breeding season for the expanding Patagonia colony are similar to those for declining southern elephant seal populations elsewhere.     

A BIBLIOGRAPHY RELATING TO THE ECOLOGY AND ENERGETICS OF EAST AFRICAN LARGE MAMMALS

Many investigations have made contributions to an understanding of energy flow through large mammals in East African ecosystems. This paper lists references to such works and compiles them according to their application to various segments as they appear in an energy-flow model. The first part indicates papers on pasture utilization, value of foodstuffs, animal numbers and distribution, population dynamics and secondary production. The second part assembles references dealing with individual animal species, stratifying them according to the subjects of ecology, food habits and nutrient utilization, population dynamics and growth.     

A COUNT OF THE LARGE MAMMALS OF THE LAKE MANYARA NATIONAL PARK: RESULTS AND DISCUSSION

1. The method of counting the large mammals in Lake Manyara National Park is described.
2. The results of the count are listed, and the biomass estimated.
3. It is suggested that the present population exceeds the carryingcapacity because elephant and buffalo are being made to enter and stay in the Park by increasing cultivation round the boundaries.
4. The rise in lake level has aggravated the position by cutting off another route of entry an d exit.
5. The extinction of the plains game population is likewise attributed to the new lake level and increased cultivation.     

中国北方"第四纪(或亚代)"环境变化与大哺乳动物演化

地质年表2004的筹备和发表使关于“第四纪”概念、时限、阶元的讨论达到了高潮。目前的情势是,其下限下移至～2．6 Ma几乎已成定局;其阶元究竟是“纪”还是“亚代”正在表决中(初步表决倾向于后者)。这样一来,“第四纪”就包括以海相地层为基础建立的晚上新世、更新世及全新世三大部分。中国北方“第四纪”大哺乳动物的研究已有很长的历史。现在应该根据新的情势重新审视其演化的阶段性及其与～2．6 Ma以来环境变化之间的关系。对环境变化和大哺乳动物化石已有资料的分析表明:1)-2．6 Ma是北极冰盖大规模扩大,季风气候急剧加强,黄土开始在中国北方大面积沉积,哺乳动物群发生重大变化的时期。大量三趾马动物群特有的成员在此之前灭绝。2)～2．6至1．3 Ma是古老“第四纪”类型繁盛的时期。真马(Equus)和巨颏虎(Megantereon)从北美经过白令陆桥进入欧亚;一大批欧亚大陆起源的新属出现,如Eirictis,Meles,Crocuta,Coelodonta,Eucladoceros,Elaphurus,Leptobos等。这一时期后期的气候,从黄土粒度曲线变化幅度普遍较小判断,应该相对比较稳定,较为温和。3) 1．3-0．13 Ma为中华大角鹿(Sinomegaceros)异常繁盛的时期。一大批以周口店动物群为代表的典型中更新世的种类出现,如与狼接近的变异狼、中国硕鬣狗、意外巨颏虎、基什贝尔格犀等。这一时期之初有相当数量的东洋界分子越过秦岭进入中国北方的南部,如大熊猫、东方剑齿象、巨貘、毛冠鹿、鬣羚等。这一时期的气候起伏大,有明显逐渐变冷的趋势。从黄土粒度曲线看,至少有3次明显的冷期和一次较长的暖期(L15,L9,L2和S5)。因此,这一阶段是可以再分的,但这需要对哺乳动物化石和动物群的年代进行更为深入的研究。4)0．13～ 0．011 Ma出现大量现生种,如普氏野马、野驴、野猪、盘羊等;一些晚更新世特征的类型出现, 如猛犸象、原始牛和具有奇特角枝的中华大角鹿等;在东北还出现了驼鹿化石。这一时期的气候波动不大,相对较温和。哺乳动物群所反映的特点应该是适应于寒冷气候的动物在较温和的气候条件下的辐射适应与新生现生种类的混合。5)0．011 Ma～现代,适应于寒冷气候的特殊类型,如猛犸象、披毛犀等灭绝。上述4个哺乳动物演化阶段自下至上可以NCMQ1～4代表之。其中NCMQ1-2之间的界限与现在“第四纪”所包含的晚上新世—早更新世及早—中更新世的界限(1．8 Ma和0．78 Ma)并不一致。这种划分和北美及欧洲的哺乳动物分期都比较接近。北美的Blancan和Irv- ingtonian的分界约为1．35 Ma;而欧洲维拉方期的顶界也在1．1～1．4 Ma之间。NCMQ3和 NCMQ4则与晚更新世及全新世相对应。     

THE TROPHIC ROLE OF MARINE MAMMALS IN THE NORTHERN GULF OF ST. LAWRENCE

The trophic role of apex predators was evaluated in the northern Gulf of St. Lawrence ecosystem. An Ecopath model was developed for the period 1985–1987 prior to the collapse of commercially exploited demersal fish stocks in this area. Marine mammal trophic levels were estimated by the model at 4.1 for cetaceans, 4.4 for harp seals (Pagophilus groenlandicus), 4.7 for hooded seals (Cystophora cristata), 4.5 for gray seals (Halichoerus grypus), and 4.3 for harbor seals (Phoca vitulina). Harp seals were the third most important predator on vertebrate prey following large Atlantic cod (Gadus morhua) and redfish (Sebastes spp.). Different seal species preyed on different levels of the food chain. Harp seals preyed on most trophic groups, whereas larger seals, such as gray seals and hooded seals, mainly consumed higher trophic levels. The model suggested that apex predators had a negative effect on their dominant prey, the higher trophic level fish, but an indirect positive feedback on the prey of their preferred prey, mainly American plaice (Hippoglossoides platessoides), flounders, skates, and benthic invertebrates. Our results suggest that both marine mammals and fisheries had an impact on the trophic structure.     

ESTIMATION OF BODY MASS IN THE SOUTHERN ELEPHANT SEAL, MIROUNGA LEONINA, BY PHOTOGRAMMETRY AND MORPHOMETRICS

A simple photographic technique was developed to indirectly estimate body mass data for southern elephant seal ( Mirounga leonina ) cows (postlactation), yearlings, and immature males and females. Regressions of mass on both photographic and morphometric variables (together and separately) yielded useful, predictable models. Using such variables, the best estimation of the actual mass was for postlactation cows, with a 95% confidence interval of ± 2.66% of the predicted body mass. Although combining photographic and morphometric variables produced the most reliable models specifically for cows and yearlings, the most practical model contained only the morphometric variables length and girth squared. Side area was the best correlated single photographic variable and this corresponded with other studies. Photogrammetry could be useful when animals cannot be sedated and are located on a flat surface, but it does require animals to be motionless when approached. Thus, the procedure may be more suited to bulls rather than other age classes and could have a role in studies where large numbers of mass estimations are rapidly required. If sedation is utilized in smaller animals, then the use of body length and girth is the most suitable indirect mass estimation technique to avoid the use of heavy weighing equipment.     

FIELD IMMOBILIZATION OF FREE-RANGING IMPALA IN NORTHERN KENYA

Two drug combinations were tested during 18 field captures of 14 individual impala in northern Kenya in 1966–67. Nine additional impala, eight females and one male, were darted but not captured. Dosages of 0.45 mg M.99+10.0 mg acepromazine+4.5 mg hyoscine were adequate for males, but did not completely immobilize them. Females proved more difficult to capture, and all attempts using the acepromazine mixture were unsuccessful. The substitution of phencyclidine for acepromazine, and the deletion of hyoscine, proved a more suitable mixture. A dosage of 0.32 mg M.99+90 mg phencyclidine per animal completely immobilized both sexes. The phencyclidine-M.99 mixture was judged an improvement over other common field immobilizing drugs, but the long recovery time limits the usefulness of this drug combination for large-scale capturing operations.     

MOVEMENTS OF SOUTHERN ELEPHANT SEALS AND SUBANTARCTIC FUR SEALS IN RELATION TO MARION ISLAND

Based primarily on an intensive marking/resighting program conducted at Marion Island (46°54'S, 37°45'E) in the Southern Ocean, the inter-island movements of southern elephant seals, Mirounga leonina , and fur seals Arctocephalus spp., were investigated to elucidate their little known pelagic phase. Southern elephant seals, in particular immature animals, readily move between the proximate Marion and Prince Edward islands. Some range as far afield as Iles Crozet, approximately 1,000 km distant where they haul out for the summer molt or during an autumn resting phase. The exchange of individuals between Marion Island and Iles Crozet during the return of immatures for the molt after a winter at sea, suggests overlapping of the foraging ranges of the two populations. Despite their wanderings, the majority of M. leonina from Marion Island probably feed in the proximity of the island, and relocate onto the island for breeding, molting and resting. Of the fur seals, only a few A. tropicalis were seen away from their natal island, in some cases covering distances in excess of 2,000 km. displaying a remarkable dispersal capacity.     

THE FEEDING HABITS OF THE YELLOW-NECKED SPURFOWL (PTERNISTIS LEUCOSCEPU8) IN NORTHERN TANZANIA

In late 1984 and throughout 1965 the feeding habits of Pternistis leucoscepus were studied in the north of Tanzania and in the Tsavo West National Park in Kenya. The main food of this bird was found to be the corms of the sedge Cyperus rotundus. Grass and legume seeds and insects formed a small proportion of the diet. P. leucoscepus is not dependent on free water and can occupy waterless country. The species' main habitat is the edge of flood plains with abundant C. rotundus sedge, bounded by shrub and small tree cover. In the two main study areas, Ngase-rai and Tarangire, the difference in the general density of the habitats is reflected in the occurrence of P. leucoscepus and Francolinus sephaena together in the former area, and of P. leucoscepus, P. cranchii, F. sephaena and F. hildebrandti in the latter. The sympat-ric occurrence of these related game birds and the apparent similarity of the two spurfowls' feeding habits presents a fascinating ecological problem for further study.     

GENETIC RELATEDNESS OF TWO POPULATIONS OF THE SOUTHERN ELEPHANT SEAL, MIROUNGA LEONINA

Blood samples from southern elephant seals ( Mirounga leonina ) from Heard and Macquarie Islands were surveyed electrophoretically for protein variation. Thirty proteins encoded by a minimum of 35 loci were screened, four of which were found to be polymorphic. Statistically significant differences in allele frequencies were found between the two populations at three loci. Heterozygosity estimates for the Heard and Macquarie island populations were 0.034 ± 0.020 (mean ± standard error) and O.029 ± 0.017 respectively, with a Nei distance of 0.007. The findings suggest that the two populations may have diverged genetically and very limited gene flow exists between the islands, a finding consistent with limited information from mark-recapture studies.