IntroductionAn investigation of the social structure and population dynamics of the desert-dwelling giraffe populations of the ephemeral Hoanib and Hoarusib Rivers in north-west Namibia.
The project aims to contribute towards the long-term conservation of the desert-dwelling giraffe through better understanding of their social structure, population dynamics and competition with other animals. The research also feeds into a larger continuous country-wide population status and assessment of giraffe in Namibia, as well as adding data to a continent-wide project (Giraffe Database) being compiled under the banner of the GCF and IUCN Species Survival Commission (SSC) Giraffe and Okapi Specialist Group (GOSG).
Researcher: Emma HartCountry: Hoanib and Hoarusib River catchments, Kunene Region, Namibia
Partner Organisations: Giraffe Conservation Foundation (GCF), Namibia
BackgroundGiraffe numbers are declining dramatically across the African continent. Current estimates suggest that 90 000 individuals remain in the wild, a figure that represents an overall decrease of greater than 35% in the past two decades. However, relative to other large African mammals, our understanding of giraffe remains limited by a lack of behavioural research. As giraffe numbers continue to fall there is a pressing need for investigations to inform conservation efforts. This study seeks to target a number of key gaps in our understanding of this iconic mammal by providing novel insights into their population dynamics and social structure.
Pilot research and anecdotal evidence suggest that giraffe may have a complex and constant fission-fusion model of social organisation. The fission-fusion model, also observed in other social mammal societies, proposes that individuals move freely within and between subgroups that are themselves embedded within a larger, more constant social network. Additional anecdotal evidence, coupled with a growing body of pilot studies conducted on captive giraffe, points to the existence of further complex relationships in giraffe society, such as those based on pair bonds, leadership and kinship. As such there is a growing argument that giraffe associations are non-random but rather are preferential and consistent over time.
It has further been proposed that in order to maintain such organised societies, giraffe are likely to have sophisticated communication systems (as in African elephants for example). These theories contradict the long-held consensus that giraffe society is formed of loose, rather than preferential, associations. If this is the case, it would have a direct bearing on conservation and population management efforts including translocation and culling events, and the transmission of infectious disease. However, there currently exists little scientific evidence to either support or refute these claims.
In summary, while research into giraffe social organisation remains in a nascent form, the suggestion is that giraffe society is considerably more complex than previously believed. There is therefore a pressing need for research into these important aspects of giraffe behaviour. The project seeks to meet this need and thus to better inform future conservation efforts, especially for the unique desert-dwelling giraffe of north-west Namibia.
ObjectivesTo investigate population dynamics and social networks of the desert-dwelling giraffe populations, including their relation to ecological determinants, competition and predation. This will include:
o Fieldwork (data collection from observations, DNA biopsy sampling, GPS-satellite collared giraffe)
o Advanced data analysis e.g. GIS, Social Network Analysis, Association Indices, genetic analysis
o Training of Namibian students and community game guards
o Research dissemination
MethodologyThe researcher is applying research methodologies that have been developed by the GCF and approved by the Ministry of Environment and Tourism (MET). Social structure is being investigated using Association indices (AI) and Network Analyses calculated on the basis of behavioural data from field observations. Genetic samples (from skin biopsies collected using a remote biopsy-dart delivery system) will be analysed to investigate the effect of relatedness on any preferred associations.
Population dynamics are being investigated through mapping and analysing giraffe individuals and observed herds using a Global Positioning System (GPS). GPS coordinates and relevant biodata will be stored in a database and coordinates mapped using a Geographical Information System (GIS) programme. Data from giraffe previously collared by GCF will also be analysed.
With the generous support of the Wilderness Wildlife Trust as well as by the Giraffe Conservation Foundation (GCF), this study is going from strength to strength. The first few months of the year were taken up by the development of a database of the giraffe that inhabit the large study area. With this in place, and with the help of both Namibian students and international volunteers, data collection began on each individual giraffe.
Since July 2016, continuous data has been collected (including data on movements, herd structure, age, size and DNA) on over 280 individual giraffe. The aim is to continue to collect and analyse this data over the coming three years, a process that will allow publication on new and exciting insights into giraffe behaviour and genetics.
Between July and September, five giraffe were also fitted with GPS satellite collars. These collars are providing regular data on the giraffes’ movements, allowing deeper insights into how they use their environment.
The project has offered opportunities for Namibian students to gain experience in cutting-edge conservation research. An Honours student in Nature Conservation and a Master’s student in Remote Sensing joined the project; both students are enrolled in the Namibian University of Science and Technology (NUST).
The past two field trips have seen the rivers in flood in the study area, and rain falling across the plains. While this marks the end of the drought and is good news for giraffe in the short-term, giraffe face longer-term threats to their survival.