Researcher: John and Kerryn CarterRegion: Etosha National Park, Namibia
BackgroundPreviously, giraffe societies were considered to show weak bonds between individuals and families. However, recent research seems to indicate that they may be more complex than previously thought; further studies are needed to increase our understanding of the social dynamics of these herbivores. Research of captive female giraffe suggests that adult females that associate with each other may be close relatives that can communicate with each other when they are apart, using low-frequency sounds.
This study aims to document the social relationships of approximately 135 wild female giraffe in Etosha National Park, Namibia. It is hoped that the research will reveal more about the social organisation of female giraffe by studying their ‘social network’. This knowledge will be valuable for the management and conservation of giraffe populations going forward, including the relocation of giraffe groups, where a better understanding of their social factors may be vital for their survival. For example, past studies of elephants have shown that relocations are more successful if the entire elephant family is moved rather than random individuals. Little has been published about the effect of translocations for giraffe societies and this study will provide important information for conservation efforts.
From a conservation perspective, future relocations of giraffe Africa-wide may be needed because the population as a whole is decreasing in numbers and some subspecies are already endangered (e.g. the Niger giraffe). With recent recognition of the strong genetic distinctions between subspecies of giraffes and the current push for reclassification of the six subspecies to full species status, governments will be motivated to implement conservation programmes for the most threatened populations.
There is a strong need to improve our knowledge about the importance of giraffe sociality before existing populations are broken up by removal of individuals for translocation, to ensure that the social groups that are relocated have the correct social structure to ensure long-term survival.
MethodologyA first in the research field is the use of a multi-method approach to understand the social structure of a species. Project objectives will include identifying each individual by coat pattern; observing which giraffe spend more time together and testing their DNA to see if they are relatives; investigating the benefits of being with other giraffe and why some females may have more ‘friends’ than others; observing who maintains the friendships; and finally, producing a model of the giraffe ‘social network’.
At each sighting of a giraffe group, the identity of all individuals will be recorded, along with its GPS location and the activity of the group, such as feeding or travelling. The reproductive state, age, height and condition of all females will be recorded. Once group members have been recorded, observations of randomly selected (focal) individuals will be carried out for 20 minutes each.
The following data will be also be recorded: time spent vigilant, feeding and travelling and two-minute scan samples – the latter includes the identity of all giraffe within a radius of 15m of the focal individual and the identity of the closest giraffe to the focal individual; all social interactions involving bodily contact with the focal animal and individuals feeding on the same food source with the focal animal; all approaches and retreats between the focal individual and other individuals within 15m.
Skin biopsies will be collected from subadult and adult female giraffe. Understanding if female giraffe associate closely with each other because they are related is an important part of the overall project. Some evidence points towards the existence of a matrilineal social structure (generations of female descendants), since young female giraffe have been recorded associating with their mothers in the wild, whereas males are likely to leave female groups at an early age.
The genetic work will have two phases: Phase one will develop new microsatellite markers for Namibian giraffe to enable us to complete genetic analysis of relatedness within the study population. Namibian giraffe are known to show low genetic variation and previous work has shown that the microsatellite markers that are currently available will not be sufficient for a successful assignment of relatedness.
454 sequencing will provide the sequences that are required to develop new microsatellite markers. Once these sequences have been obtained, 60 primer sets will be used to test a subset of samples to find appropriate microsatellite markers to use for analysis.
The first phase will provide vital information for the second phase which will involve extracting DNA, completing genetic analyses and assessing the degree of relatedness between particular individuals.
Kerryn Carter published her PhD on this study.
The Trust provided funding for the world’s first Wild Giraffe Indaba, which took place at the Etosha Safari Lodge over the 4 – 7 July 2011. The Indaba was a huge success and a step in the right direction for giraffe conservation as a whole.
The Giraffe Indaba was great success with over 30 giraffe researchers and experts from 11 countries attending. The conference was not only limited to fascinating presentations and the delivery of research papers covering a breadth of topics, but also included interactive workshop sessions on taxonomy, genetics and research technology, with many of these discussions extending late into the evenings around the open fire.
It was abundantly clear from the conclusions to many presentations and certainly as a result of the forums, that there remain a worryingly large amount of questions about giraffe research and conservation management still unanswered. Appropriately entitled Giraffe: The Forgotten Megafauna, it is clear that this Indaba, the first ever of its kind, was long overdue and could not have come at a more critical time. With giraffe numbers across the continent estimated below 80,000, down from some 140,000 at the turn of the century, there is a clear requirement to reverse, or at last halt, this alarming decline.
It is of little surprise then that the highlight of the Indaba was the final day’s workshop on establishing a long overdue ‘road-map’ document, detailing short- to medium-term research goals focussing specifically on the long-term understanding of giraffe in their natural habitat, and essentially developing a conservation management strategy framework.
The project has completed another year of study on the female giraffes in Etosha National Park. The identification catalogue of giraffe observed in the Okaukuejo area now includes 250 adult and sub-adult females and 65 juveniles. Work has begun on the genetic analysis of relatedness between female giraffe, which will help our understanding of the social bonds formed, if any, between related females. We have used new sequencing technology to isolate potential genetic markers from giraffe tissue DNA, and in early 2011 these will be tested to find the best microsatellite markers for the overall analysis. These will be the first genetic markers developed for this Namibian subspecies and once developed, they will be made available to the genetic community for future studies of giraffe.
In the field, analysis of data has found that adult female giraffe benefit when foraging in a group because they are able to spend more time feeding and less time looking for predators when another giraffe is feeding nearby, but as the distance from others increases, an individual will spend more time scanning the environment and less time feeding. This behaviour suggests that giraffe feel more secure in the presence of others; however the numbers of giraffe in the group has no effect on this anti-predator behaviour, so it appears that safety in numbers is not an important factor for giraffe. In addition, it was found that female giraffe with young calves incur an energetic cost through increased vigilance as they cannot spend as much time feeding as other giraffe as they are continually checking their surroundings for threats, even if other giraffe are nearby. These initial findings will be further investigated in 2011.
The aims for the next year are to look at the strength of relationships between pairs of giraffes and produce social networks of giraffes, looking at how different seasons, reproductive states of females (i.e. heavily pregnant or with small calf) and relatedness between females affect their social bonds over time. This will provide a greater understanding of what factors are important in female giraffe societies.
To date, skin biopsies have been collected from 70 subadult and adult female giraffe. Understanding if female giraffe associate closely with each other because they are related is an important part of the overall project. Some evidence points towards the existence of a matrilineal social structure (generations of female descendants), since young female giraffe have been recorded associating with their mothers in the wild, whereas males are likely to leave female groups at an early age.
Funds from the Trust were used to purchase primer sets for the development of new microsatellite markers for the Namibian giraffes. Informative markers for this subspecies do not yet exist, however once developed, will be made available to any future researchers wishing to study G.c.angolensis. This will enable us to complete the genetic analysis of relatedness.
In the seven months since the project began (May 2009) in Etosha National Park, 115 adult females with their offspring and 30 sub-adult females have been identified and catalogued. Interestingly, 61 of these adult females were known to be present in the study area in 2004/2005, suggesting a stable ranging pattern and site fidelity for these individuals. However, approximately half the adult females that have now been seen in the study area were not present four years ago, which may indicate immigration of female giraffe from other areas.
Data is gradually building regarding the strength of associations between individual females, and it is clear that there are stronger bonds between some pairs of giraffe than others. For example, female giraffe with young foals have been recorded associating in pairs over a number of days, and this may be because they have similar nutritional or anti-predator needs as a result of having young foals. There is also some evidence that older adults hold leadership roles and make decisions about movement of the group between feeding patches, suggesting that younger giraffe follow those with more experience.
The aims for the next year are to complete data collection through all seasons to study giraffe interactions with each other and whether this changes by season, to analyse their social network, and to understand what is important in female giraffe societies. Following this, it is hoped that DNA analysis of relatedness between females will increase understanding of the bonds formed, if any, between related females.