Taming of the Shrew
Category: Coastal Forest, Elephant Shrew, Shimoni Forest, Shrews, Small mammals | Date: Nov 17 2009 | By: gvikenya
For about a year now we’ve been experimenting with a method of trapping the elusive and shy Zanj elephant shrew. This particular shrew is technically a sengi, and is a species that is not only endemic to the east African coast, but is also listed as ‘rare’ and ‘data deficient’ by the IUCN.
Shimoni forest boasts a significant population of this small mammal, and sightings of it by our forest teams are fairly regular (especially at this time of year when visibility is good). So we did some research and decided to procure ourselves a 50m long, very finely threaded fishing net with which to catch them with!
One of the cleared patches that mark the habitual pathway
We set the net up in a large semi circle, and either ‘beat the bush’ towards the net hoping to drive a shrew into it, or we sit nice and quietly and wait for one to wander in. This method works because the Zanj elephant shrew uses habitual pathways, which it will travel along each day clearing them of obstacles. So if one was to encounter the net, it would most likely attempt to get through or over the net, causing it to get entangled. Once caught we would take its measurements, weight, and then clip a small patch of fur on a designated spot on its body for mark-recapture purposes.
Some zanj elephant shrew droppings that are found around the paths
Unfortunately we haven’t caught one yet, but I do not doubt the method itself. Due to the amount of time needed to complete all of our regular surveys, we only get a chance to do this survey perhaps once or twice every three months. This is obviously not even remotely enough to stand a chance of catching a shrew. Especially because until recently we did not know what their trails looked like and therefore could not strategically place our net.
But a couple of weeks ago we saw one of the little chaps running away from us, and so we had a closer look at the exact route it took through the undergrowth. To our surprise, the path was quite obviously marked. Approximately every 30cm, there is a cleared area of dirt. A patch where all the leaf litter and twigs and other debris is cleared, leaving a bare area of dirt approximately 10cm long. And these cleared patches headed off into the undergrowth!
Several of the patches leading off into the undergrowth
Now we know what to look for, we have been spotting the shrew trails all over the forest! This has given us motivation to get back into shrew netting, and allowed us to strategically place our net across these trails, greatly increasing our chance of catching one!
We’ll keep you posted!
Tags: , beat the bush, data deficient, debris, droppings, East African Coast, elusive, endemic, entangled, fishing net, good visibility, habitual pathways, IUCN, leaf litter, mark-recapture, measurments, method of trapping, obstacles, rare, regular surveys, research, sengi, Shimoni Forest, shrew netting, shy, significant population, small mammal, strategically, trails, twigs, undergrowth, weight, zanj elephant shrew
Bottlenose Abundance In Kenyan Coastal Waters
Category: Cetacean research, Dolphins, Kenya Wildlife Service, Kisite Mpunguti MPA, bottlenose dolphins | Date: Oct 14 2009 | By: gvikenya
Kisite-Mpunguti Marine Protected Area (KMMPA) lies south of Wasini Island (south-coast of Kenya) and covers an area of 39 square kilometres. The KMMPA includes the National Park surrounding Kisite Island and the Marine Reserve surrounding the Mpunguti islands. The KMMPA and the marine wildlife it contains are an important tourist attraction and, as a result, an important resource for Shimoni and surrounding communities. The islands within the KMMPA are surrounded by coral reefs attracting divers and snorkelers to the area. Almost every day dolphin-watching companies operating from Shimoni travel through Wasini Channel to the KMMPA. These tourist dhows most frequently encounter Indo-Pacific bottlenose dolphins (Tursiops aduncus), and less frequently, Indo-Pacific humpback dolphins (Sousa chinensis).
Global Vision International (GVI) Kenya’s main working partner is the Kenya Wildlife Service (KWS). The research conducted by GVI is shaped to satisfy the objectives of KWS, so as to assist them towards better management of the area. All data collected thus far is made available to KWS to aid in management plans of the study area. The Marine Programme is supporting KWS to collate data by conducting vessel surveys, which was focus on assessing the bottlenose dolphin abundance on the area, during the initial phase.
After three years of cetacean research in Kisite-Mpunguti MPA, GVI has estimated the absolute abundance of bottlenose dolphins around 122 individuals, being the second biggest population of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in East Africa. The largest population of the species inhabits in Kizimkazi (south-coast of Zanzibar), and holds between 139 and 179 individuals (estimation made by University of Stockholm in 1999-2002).
Photo-id and mark-recapture methods were the methodology used on both studies to get the estimation. Photo-ID refers to the identification of individuals by distinctive features (shape, outline, natural markings and scarring) of their dorsal fins, flanks and flukes. Some scars will be retained through life, whereas others will be added and may fade through life. The depth and severity of the wound will determine the length of time this may be used for identification. These features allow known individuals to be re-sighted. The re-sighting rate can be plotted on a discovery curve, the plateau of which suggests population size. Photo-ID can also be used to determine residency and demographic data such as inter-birth intervals, patterns of ranging and mortality.
Mark-recapture methods are used to calculate population size from the proportion of known individuals re-sighted over the study period. Mark-recapture models estimate only the size of marked individuals in the population. Therefore, the total population size has been corrected by the correction factor.
Kenya Wildlife Service applied a code of conduct in 2007 for the tour operators to follow when manoeuvring around the cetacean species; unfortunately it is not being fully adhered to as it has only recently been implemented. The levels of interaction between cetaceans and the tour operators are not being monitored or regulated in any way. The impact these activities may be having is unknown. In particular, it’s not known whether current levels of dolphin tourism are sustainable for the area. The first estimation of Indo-Pacific bottlenose dolphins in KMMPA will allow GVI and KWS to measure the levels of tourism impacts, analysing the population dynamics of this species.
Tags: absolute abundance, coral reefs, correction factor, demographic data, depth, divers, dorsal fin, identification, Indo-Pacific bottlenose dolphins, inter-birth intervals, Kenya, Kenya Wildlife Service, kisite island, marine programme, marine reserve, mark-recapture, mpunguti island, national park, photo-ID, severity, shimoni, snorkellers, south coast, surveys, University of Stockholm, wasini channel, wasini island
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