Henrik Rasmussen

Savannah Tracking · R&D

Advances in the technology of biotelemetry are transforming the ways in which we remotely acquire environmental, physiological and behavioural data. Large and heavy batteries, however, continue to reduce the availability of GPS tracking devices for small taxa and for species with morphologies that limit attachment options. Device miniaturisation is...

Poaching is one of the primary drivers of wildlife decline [1]. Animalborne sensors, particularly GPS-equipped collars, are used to enhance real-time wildlife protection. Innovations that can be integrated into these systems can immediately scale, offering broad application. GPS tracking data streams have been valuable to resolve a number of conser...

Wildlife poaching is a critical driver of biodiversity loss and population decline. Poaching is a particular threat to high value, large-bodied species, such as elephants, that are slow to reproduce. Increasingly, GPS tracking collars serve as a key tool for studying the behavior and monitoring wildlife globally, including application to anti-poach...

The drivers of social affiliation may vary over time as individuals change their goals with respect to changing environments or physical condition. Studies of companion preference rarely consider shifts in motivational state, despite the potential importance of such shifts in structuring association and population processes. Ignoring state dependen...

African swine fever virus (ASFV) is a serious animal disease of pigs, causing high mortality in domestic swine. In Africa, the presence of a sylvatic cycle involving wild pigs and soft ticks means that the risk of introduction of ASFV into domestic swine is always present. Although warthogs are considered the main wild vertebrate host of the virus...

We investigated the ranging patterns of elephants in the Marsabit protected area, north eastern Kenya, to ascertain the range of bachelor and female family herds in different seasons, and to identify corridor and noncorridor areas. Data were acquired for five bachelor and four female family herds equipped with satellite-linked geographical position...

Hierarchical properties characterize elephant fission-fusion social organization whereby stable groups of individuals coalesce into higher order groups or split in a predictable manner. This hierarchical complexity is rare among animals and, as such, an examination of the factors driving its emergence offers unique insight into the evolution of soc...

Hormones play a crucial role in mediating genetic and environmental effects into morphological and behavioral phenotypes. In systems with alternative reproductive tactics (ART) shifts between tactics are hypothesized to be under proximate hormonal control. Most studies of the underlying endocrine changes behind ART have focused on fish and amphibia...

Two hundred years of elephant hunting for ivory, peaking in 1970-1980s, caused local extirpations and massive population declines across Africa. The resulting genetic impacts on surviving populations have not been studied, despite the importance of understanding the evolutionary repercussions of such human-mediated events on this keystone species....

We investigated population genetic structure and regional differentiation among African savannah elephants in Kenya using mitochondrial and microsatellite markers. We observed mitochondrial DNA (mtDNA) nucleotide diversity of 1.68% and microsatellite variation in terms of average number of alleles, expected and observed heterozygosities in the tota...

Information on age- and tactic-related paternity success is essential for understanding the lifetime reproductive strategy of males and constitutes an important component of the fitness trade-offs that shape the life-history traits of a species. The degree of reproductive skew impacts the genetic structure of a population and should be considered w...

The phenology of reproduction is often correlated with resource availability and is hypothesized to be shaped by selective forces in order to maximize lifetime reproductive success. African elephants have the distinctive life history traits of a 22 month gestation and extended offspring investment, necessitating a long-term strategy of energy acqui...

Models of wildlife population dynamics are crucial for sustainable utilization and management strategies. Fluctuating ecological conditions are often key factors influencing both carrying capacity, mortality and reproductive rates in ungulates. To be reliable, demographic models should preferably rely on easily obtainable variables that are directl...

We use chronologies of stable isotopes measured from elephant (Loxodonta africana) hair to determine migration patterns and seasonal diet changes in elephants in and near Samburu National Reserve in northern Kenya. Stable carbon isotopes record diet changes, principally enabling differentiation between browse and tropical grasses, which use the C3...

In this paper, we present a new method for estimating elephant densities by counting elephant wells and dung boli within dry seasonal flooding rivers. A combination of aerial and ground counts of elephant wells and dung boli in the Ewaso Ngiro River were related to elephant numbers, obtained from an on-going monitoring program of individually ident...

High precision condensation dental silicon, ZetalaborTM, was used to create moulds of the lower jaw molars from 22 immobilized African elephants (Loxodonta africana Blumenback) during radio collaring operations. These moulds were used to determine the elephant's age using Laws and Jachmann's molar aging criteria. The technique proved easy and fast...

Individual based demographic records of the elephants utilizing Samburu and Buffalo Springs National Reserves were collected from 1998 through 2003 and indicate that this elephant population was increasing at an average rate of 4.6% per year. Although the majority of carcasses were not found, known sources of mortality include disease, injury, and...

Musth in male African elephants, Loxodonta africana, is associated with increased aggressive behavior, continuous discharge of urine, copious secretions from the swollen temporal glands, and elevated androgen levels. During musth, bulls actively seek out and are preferred by estrous females although sexual activity is not restricted to the musth co...