The Experts below are selected from a list of 867 Experts worldwide ranked by ideXlab platform
Fred B. Bercovitch - One of the best experts on this subject based on the ideXlab platform.
-
Movement patterns and herd dynamics among South African giraffes (Giraffa camelopardalis Giraffa)
African Journal of Ecology, 2018Co-Authors: Francois Deacon, Fred B. BercovitchAbstract:Giraffes reside in a fission–fusion social system, with sex, age proximity, kinship and home range overlap accounting for some of the variance in herd composition, while season, sex, age and time of day influence diet, home range size and distance travelled. To increase our knowledge of habitat use and fission–fusion herd dynamics, we placed GPS devices on eight adult female South African giraffes (Giraffa camelopardalis Giraffa) living in the Khamab Kalahari Nature Reserve (South Africa). We tested four predictions about how season, kinship, home range and travel patterns influence habitat use and herd dynamics. Our two key findings were that females with a greater degree of home range overlap were more likely to form herds, but the degree of overlap was independent of the amount of time that they spent together in a herd, and that on the day prior to herd formation, females travelled about twice as far as their daily average and tended to move directly towards their future herd mate. We conclude that habitat use and movement patterns regulating fission–fusion dynamics reflect an interaction of ecological, social and reproductive factors operating in tandem, not independently.
-
population census of thornicroft s giraffe Giraffa camelopardalis thornicrofti in zambia 1973 2003 conservation reassessment required
Oryx, 2016Co-Authors: Philip S. M. Berry, Fred B. BercovitchAbstract:Thornicroft's giraffe Giraffa camelopardalis thornicrofti is limited in distribution to a single population resident in the Luangwa Valley, Zambia. During 1973−2003 regular counts were recorded along the Luangwa River in the core section of the subspecies’ range. In 2013 we conducted a count in the same region for comparison with the earlier survey results. During the 30-year period 1973−2003 the giraffe index (no. of individuals per km surveyed) was relatively stable, with an increase in 1994 and 1995 coinciding with an influx of giraffes to the west bank following an exceptionally reduced flow of the Luangwa River. The mean giraffe index during this period was 0.51 km −1 , whereas the 2013 count yielded an index of 0.44 km −1 . Given the limited range of the Thornicroft's giraffe, we estimate that the population comprises c. 500–600 individuals.
-
Concurrent Pregnancy and Lactation in Wild Giraffes (Giraffa camelopardalis)
African Zoology, 2015Co-Authors: Francois Deacon, Pierre J Nel, Fred B. BercovitchAbstract:Lactation boosts reproductive costs by depleting maternal condition and delaying subsequent conception. However, some evidence suggests that giraffes (Giraffa camelopardalis) have evolved a mechanism to minimise the time allocated to suckling-induced suppression of ovulation. Here, we show for the first time that wild giraffe cows are impregnated while nursing a young calf. We suggest that a trio of traits (non-seasonal breeding, slow embryonic development and rapid calf growth) have promoted this unusual and flexible female reproductive strategy.
-
The structure of social relationships among captive female giraffe (Giraffa camelopardalis).
Journal of Comparative Psychology, 2007Co-Authors: Meredith J. Bashaw, Mollie A. Bloomsmith, Terry L. Maple, Fred B. BercovitchAbstract:Giraffe herds have been characterized as random associations of individuals, but recent evidence suggests giraffe have a more complex social structure. The authors formulated 3 hypotheses designed to evaluate whether a herd of captive giraffe (Giraffa camelopardalis) associated randomly or patterned their behavior and proximity in a manner indicative of social relationships. Affiliative interaction, proximity, and nearest neighbors for 6 captive female giraffe living in a large outdoor enclosure were analyzed, and all three measures were nonrandomly distributed, indicating female giraffe had social preferences. Furthermore, preferences were consistent across measures and time, suggesting that adult female giraffe maintain relationships. Mother-daughter pairs and pairs with large age differences between members interacted and associated most often. The social structure of this captive herd is influenced by social relationships between individual adult females, and the social behavior of individual females should be examined more closely in the wild.
Axel Janke - One of the best experts on this subject based on the ideXlab platform.
-
mitochondrial sequences reveal a clear separation between angolan and south african giraffe along a cryptic rift valley
BMC Evolutionary Biology, 2014Co-Authors: Friederike Bock, Francois Deacon, Julian Fennessy, Andy Tutchings, Tobias Bidon, Andri Marais, Axel JankeAbstract:Background The current taxonomy of the African giraffe (Giraffa camelopardalis) is primarily based on pelage pattern and geographic distribution, and nine subspecies are currently recognized. Although genetic studies have been conducted, their resolution is low, mainly due to limited sampling. Detailed knowledge about the genetic variation and phylogeography of the South African giraffe (G. c. Giraffa) and the Angolan giraffe (G. c. angolensis) is lacking. We investigate genetic variation among giraffe matrilines by increased sampling, with a focus on giraffe key areas in southern Africa.
-
mitochondrial dna analyses show that zambia s south luangwa valley giraffe Giraffa camelopardalis thornicrofti are genetically isolated
African Journal of Ecology, 2013Co-Authors: Julian Fennessy, Friederike Bock, Andy Tutchings, Rick A Brenneman, Axel JankeAbstract:Thornicroft's giraffe, Giraffa camelopardalis thornicrofti, is a geographically isolated subspecies of giraffe found only in north-east Zambia. The population only occurs in Zambia's South Luangwa Valley, an area which interestingly places it between the current distribution of Masai (G.c.tippelskirchi) giraffe to the north, and the Angolan (G.c.angolensis) and South African (G.c.Giraffa) giraffe in the south-west and south, respectively. Specific studies have been undertaken on the ecology of this subspecies, but their population genetics remains unknown. We studied 34 individuals from the South Luangwa National Park and adjacent Lupande Game Management Area and seven individuals from northern Botswana. The complete cytochrome b and control region sequences of the mitochondrial genome were sequenced and analysed together with database data by maximum likelihood tree reconstruction and maximum parsimony network analyses. The giraffe from Zambia's South Luangwa Valley are most closely related to the subspecies G.c.tippelskirchi and part of their radiation. However, they form a unique population that would benefit from increased research and conservation management. Resume La girafe de Thornicroft, Giraffa camelopardalis thornicrofti, est une sous-espece isolee geographiquement que l'on ne trouve qu'au nord-est de la Zambie. Cette population ne vit que dans le sud zambien de la Vallee de la Luangwa, une zone qui la situe entre la distribution actuelle de la girafe masai (G.c.tippelskirchi) au nord, celle de la girafe d'Angola (G.c.angolensis) et celle d'Afrique du Sud (G.c.Giraffa), respectivement au sud-ouest et au sud. Des etudes specifiques ont ete entreprises sur l'ecologie de cette sous-espece, mais la genetique de cette population reste inconnue. Nous avons etudie 34 individus du Parc National de South Luangwa et de l'Aire de gestion de la faune de Lupande qui lui est proche et sept individus du nord du Botswana. Les sequences completes du cytochromeb et d'une region de reference du genome mitochondrial ont ete realisees et analysees en regard des donnees de reference par des analyses par reconstruction de l'arbre selon le principe du maximum de vraisemblance et par la methode de parcimonie maximale. Les girafes de la Vallee de South Luangwa en Zambie sont plus etroitement apparentees a la sous-espece G.c.tippelskirchi et font partie de leur radiation. Cependant, elles constituent une population unique qui aurait tout interet a faire l'objet de nouvelles recherches et d'une meilleure gestion de conservation.
Jason Pootoolal - One of the best experts on this subject based on the ideXlab platform.
-
GROWTH, HUSBANDRY, AND DIETS OF FIVE SUCCESSFULLY HAND-REARED ORPHANED GIRAFFE CALVES (Giraffa camelopardalis ROTHSCHILDI AND Giraffa camelopardalis RETICULATA)
Journal of zoo and wildlife medicine : official publication of the American Association of Zoo Veterinarians, 2019Co-Authors: Janine Meuffels, Cyrillus Ververs, Jason Pootoolal, Martine Van Zijll Langhout, Jan GovaereAbstract:Giraffe in the wild are in ongoing decline because of poaching and habitat loss and fragmentation, and were recently assessed as “vulnerable” on the IUCN (International Union for Conservation of Nature) Red List of Threatened Species. Captive breeding and saving each individual are therefore becoming more important to save this species from extinction. This paper describes the husbandry and diets of successfully hand-reared Rothschild's giraffes (Giraffa camelopardalis rothschildi; n = 3) and reticulated giraffes (Giraffa camelopardalis reticulata; n = 2). All calves were initially fed with bovine colostrum followed by cow's milk (Holstein milk; Holstein milk with 10% of bovine colostrum; Jersey and Guernsey milk). Additionally, lactase enzymes (Lactaidt, Johnson & Johnson Inc., Guelp, Ontario N1K1A5, Canada) and probiotics (Probiost, Vets Plus, Inc., Menomonie, WI 54751, USA) were used. Average growth varied from 764 to 1,239 g/day from birth until 2 mo of age and between 508 and 1,161 g/day from birth until last measurement before weaning. Hand-reared calves gained up to 21 cm in height within the first month and 82–138% of their birth weight during the first 2 mo. The giraffes were weaned at 6 (n = 1), 8 (n = 3), and 11.5 (n = 1) mo and successfully socialized and introduced to other giraffes. The described diets and husbandry proved to be effective in all five calves. Large amounts of cow's milk per feeding (up to 6 L) did not result in gastrointestinal problems.
-
ovarian ultrasonography correlated with fecal progestins and estradiol during the estrous cycle and early pregnancy in giraffes Giraffa camelopardalis rothschildi
Biology of Reproduction, 2009Co-Authors: Imke Lueders, Jason Pootoolal, Thomas B Hildebrandt, Peter Rich, Charlie Gray, Cheryl NiemullerAbstract:Fecal and urinary progestin analyses have shown that giraffes express a short reproductive cycle, averaging 15 days, compared with other large ruminants. However, actual ovarian events have not been correlated with the hormonal pattern. In this study, mature cycling female Rothschild giraffes (Giraffa camelopardalis rothschildi) were repeatedly examined by transrectal ultrasonography to correlate ovarian function with changes in fecal progestin (fP4 [n c ¼ 6]) and estradiol (fE2 [n c ¼ 6]) and serum progestin (n c ¼ 2) as measured by enzyme immunoassay. Five females became pregnant and were monitored during early gestation. In this study, we discovered that hormone values for fP4 in cycling giraffes do not correlate with the classic profile of follicular development, ovulation, and luteogenesis. The corpus luteum (CL) and the next dominant follicle were forming simultaneously. A mean 6 SD peak in fE2 of 254.92 6 194.76 ng/g and subsequent ovulation occurred as early as 1 day after the fall in fP4. In pregnant giraffes, the CL reached a diameter significantly larger (mean 6 SD, 41.02 6 2.70 mm; P ¼ 0.0126) than that during the cycle (33.48 6 2.80 mm), while follicular activity and fluctuating fE2 were still present. With this research, we demonstrated that the progesterone profile typically used to characterize the ovarian cycle does not correlate with luteal development in the ovaries of this species. Furthermore, we conclude that the giraffe could have evolved a short reproductive cycle because of the almost parallel order of ovarian events. corpus luteum, estradiol, follicle, noninvasive monitoring, ovary progesterone
Julian Fennessy - One of the best experts on this subject based on the ideXlab platform.
-
mitochondrial sequences reveal a clear separation between angolan and south african giraffe along a cryptic rift valley
BMC Evolutionary Biology, 2014Co-Authors: Friederike Bock, Francois Deacon, Julian Fennessy, Andy Tutchings, Tobias Bidon, Andri Marais, Axel JankeAbstract:Background The current taxonomy of the African giraffe (Giraffa camelopardalis) is primarily based on pelage pattern and geographic distribution, and nine subspecies are currently recognized. Although genetic studies have been conducted, their resolution is low, mainly due to limited sampling. Detailed knowledge about the genetic variation and phylogeography of the South African giraffe (G. c. Giraffa) and the Angolan giraffe (G. c. angolensis) is lacking. We investigate genetic variation among giraffe matrilines by increased sampling, with a focus on giraffe key areas in southern Africa.
-
mitochondrial dna analyses show that zambia s south luangwa valley giraffe Giraffa camelopardalis thornicrofti are genetically isolated
African Journal of Ecology, 2013Co-Authors: Julian Fennessy, Friederike Bock, Andy Tutchings, Rick A Brenneman, Axel JankeAbstract:Thornicroft's giraffe, Giraffa camelopardalis thornicrofti, is a geographically isolated subspecies of giraffe found only in north-east Zambia. The population only occurs in Zambia's South Luangwa Valley, an area which interestingly places it between the current distribution of Masai (G.c.tippelskirchi) giraffe to the north, and the Angolan (G.c.angolensis) and South African (G.c.Giraffa) giraffe in the south-west and south, respectively. Specific studies have been undertaken on the ecology of this subspecies, but their population genetics remains unknown. We studied 34 individuals from the South Luangwa National Park and adjacent Lupande Game Management Area and seven individuals from northern Botswana. The complete cytochrome b and control region sequences of the mitochondrial genome were sequenced and analysed together with database data by maximum likelihood tree reconstruction and maximum parsimony network analyses. The giraffe from Zambia's South Luangwa Valley are most closely related to the subspecies G.c.tippelskirchi and part of their radiation. However, they form a unique population that would benefit from increased research and conservation management. Resume La girafe de Thornicroft, Giraffa camelopardalis thornicrofti, est une sous-espece isolee geographiquement que l'on ne trouve qu'au nord-est de la Zambie. Cette population ne vit que dans le sud zambien de la Vallee de la Luangwa, une zone qui la situe entre la distribution actuelle de la girafe masai (G.c.tippelskirchi) au nord, celle de la girafe d'Angola (G.c.angolensis) et celle d'Afrique du Sud (G.c.Giraffa), respectivement au sud-ouest et au sud. Des etudes specifiques ont ete entreprises sur l'ecologie de cette sous-espece, mais la genetique de cette population reste inconnue. Nous avons etudie 34 individus du Parc National de South Luangwa et de l'Aire de gestion de la faune de Lupande qui lui est proche et sept individus du nord du Botswana. Les sequences completes du cytochromeb et d'une region de reference du genome mitochondrial ont ete realisees et analysees en regard des donnees de reference par des analyses par reconstruction de l'arbre selon le principe du maximum de vraisemblance et par la methode de parcimonie maximale. Les girafes de la Vallee de South Luangwa en Zambie sont plus etroitement apparentees a la sous-espece G.c.tippelskirchi et font partie de leur radiation. Cependant, elles constituent une population unique qui aurait tout interet a faire l'objet de nouvelles recherches et d'une meilleure gestion de conservation.
-
Distribution and status of the desert-dwelling giraffe (Giraffa camelopardalis angolensis) in northwestern Namibia
African Zoology, 2003Co-Authors: Julian Fennessy, Keith E. A. Leggett, Stephanie SchneiderAbstract:The population density and distribution of desert dwelling giraffes was estimated in three study areas in the Hoanib River catchment, northwestern Namibia. Giraffe population densities (0.01 giraffe/km2) were equal to the lowest recorded in Africa with population numbers fluctuating over past decades. Sex ratios, herd sizes and age categories differed between all the study areas, while a weak correlation (r2 = 0.66, P < 0.001) in giraffe aggregation and the hot dry season was observed in the Ombonde River. Seasonal move ment and use of the riparian environments varied, with large fluctuations observed in the east of the catchment, while the hot dry season influx and use in the riparian woodland coincided with Faidherbia albida podding. Key words : Giraffa camelopardalis angolensis, popu lation structure, seasonal movement.
Francois Deacon - One of the best experts on this subject based on the ideXlab platform.
-
Movement patterns and herd dynamics among South African giraffes (Giraffa camelopardalis Giraffa)
African Journal of Ecology, 2018Co-Authors: Francois Deacon, Fred B. BercovitchAbstract:Giraffes reside in a fission–fusion social system, with sex, age proximity, kinship and home range overlap accounting for some of the variance in herd composition, while season, sex, age and time of day influence diet, home range size and distance travelled. To increase our knowledge of habitat use and fission–fusion herd dynamics, we placed GPS devices on eight adult female South African giraffes (Giraffa camelopardalis Giraffa) living in the Khamab Kalahari Nature Reserve (South Africa). We tested four predictions about how season, kinship, home range and travel patterns influence habitat use and herd dynamics. Our two key findings were that females with a greater degree of home range overlap were more likely to form herds, but the degree of overlap was independent of the amount of time that they spent together in a herd, and that on the day prior to herd formation, females travelled about twice as far as their daily average and tended to move directly towards their future herd mate. We conclude that habitat use and movement patterns regulating fission–fusion dynamics reflect an interaction of ecological, social and reproductive factors operating in tandem, not independently.
-
The South African giraffe Giraffa camelopardalis Giraffa : a conservation success story
Oryx, 2018Co-Authors: Francois Deacon, Andy TutchingsAbstract:Across Africa the majority of giraffe species and subspecies are in decline, whereas the South African giraffe Giraffa camelopardalis Giraffa remains numerous and widespread throughout southern Africa. By 2013 the number of giraffes in South Africa's Kruger National Park had increased by c. 150% compared to 1979 estimates. An even greater increase occurred on many of the estimated 12,000 privately owned game ranches, indicating that private ownership can help to conserve this subspecies. The estimated total population size in South Africa is 21,053–26,919. The challenge now is to implement monitoring and surveillance of G. camelopardalis Giraffa as a conservation priority and to introduce sustainable practices among private owners to increase numbers and genetic variation within in-country subspecies.
-
Concurrent Pregnancy and Lactation in Wild Giraffes (Giraffa camelopardalis)
African Zoology, 2015Co-Authors: Francois Deacon, Pierre J Nel, Fred B. BercovitchAbstract:Lactation boosts reproductive costs by depleting maternal condition and delaying subsequent conception. However, some evidence suggests that giraffes (Giraffa camelopardalis) have evolved a mechanism to minimise the time allocated to suckling-induced suppression of ovulation. Here, we show for the first time that wild giraffe cows are impregnated while nursing a young calf. We suggest that a trio of traits (non-seasonal breeding, slow embryonic development and rapid calf growth) have promoted this unusual and flexible female reproductive strategy.
-
mitochondrial sequences reveal a clear separation between angolan and south african giraffe along a cryptic rift valley
BMC Evolutionary Biology, 2014Co-Authors: Friederike Bock, Francois Deacon, Julian Fennessy, Andy Tutchings, Tobias Bidon, Andri Marais, Axel JankeAbstract:Background The current taxonomy of the African giraffe (Giraffa camelopardalis) is primarily based on pelage pattern and geographic distribution, and nine subspecies are currently recognized. Although genetic studies have been conducted, their resolution is low, mainly due to limited sampling. Detailed knowledge about the genetic variation and phylogeography of the South African giraffe (G. c. Giraffa) and the Angolan giraffe (G. c. angolensis) is lacking. We investigate genetic variation among giraffe matrilines by increased sampling, with a focus on giraffe key areas in southern Africa.