The best way to determine what a pack of wild dogs is eating is through direct observation. This method required that the dogs be intensively radio-tracked and followed by vehicle. The observations may, however, be biased towards large prey as smaller prey may be caught and consumed quickly without the observer noticing. Effectiveness of this method may be affected by vegetation and terrain. Timing and duration of observations should be carefully pre-planned and adhered to. To reduce biasing of the kill data another method should be used in conjunction with direct observations to strengthen the findings.
Identification of remains:
Wild dogs often eat, or scatter, almost the entire carcass, but if remains can be found, these could be used to identify the species killed. Tufts of hair, pieces of limbs and even spoor around the kill site can be used to determine what was killed.
Analysis of hair in scat details:
While tracking a pack of wild dogs fresh scats (fresh enough to know that they were deposited during the current observation period) can be collected to determine what that individual had eaten in the past 92 hours (average passage rate, REF) through analysis of the hair. Care must, however, be taken as scats can carry many parasites and are potential sources of disease. It is advised that one inverts the bag over one’s hand, picks up the entire scat, and pulls the bag over it. The sample can then be dried in the sun before beginning to extract the hair within. A guide to the methods involved in processing and identifying the hairs can be found in Davies-Mostert 2010, unpublished.
Basic feeding frequency data can be collected by scoring the size of wild dogs’ bellies. Such data lack detail and can only give an indication of kill rate, i.e. whether of not they have eaten since the last time they were observed. Scores, and their corresponding meanings, must be determined beforehand and used consistently thereafter.
1. Belly well above the chest line, hence ‘empty’
2. Belly level with chest line
3. Belly somewhat below the chest line but not distended laterally
4. Belly well below the chest line and distended laterally, hence ‘full’
Belly scores are based entirely on visual interpretation by the observer. It must, thus, be kept in mind that the scores are subjective. A set of photographs depicting each of the scores could be used as a reference card to improve inter-observer reliability.
Determining age and condition of prey
Use of jaw bones to age carcasses:
As ungulates age their teeth are worn at a predictable rate. Collection of the lower jaw of wild dog kills allows one to age the carcass.
Use of bone marrow to assess condition of carcasses:
The body condition of animals is reflected by the fat content of their bone marrow. The higher the fat contents the better the body condition of the animal. To assess the condition of wild dog kills bone marrow can be from any of the large bones of the carcass (preferably the femur). This is never an easy task as wild dogs are prone to scattered parts of the carcass as they feed. Without disturbing the pack too much the first opportunity to collect the bone marrow must be taken. At least one heaped teaspoon of bone marrow should be collected and frozen until ready for processing.
‘’Body condition of impala and kudu was assessed from the fat content of the femur marrow from wild dog kills (Sinclair & Duncan 1972; Brooks et al. 1977; Reich 1981b; Fitzgibbon & Fanshawe 1989; Pole et al. 2004). Fat is mobilised from the femur and humerus after the other bones and therefore the marrow in these bones is a sensitive measure of body condition (Brooks et al. 1977; Reich 1981b). Following Pole et al. (2004), a 2-10 g portion of marrow was extracted from the central section of the femur and stored in airtight containers in the freezer. Samples were then weighed to the nearest 0.1g and oven-dried until there was no further change in weight. The percentage of marrow fat was estimated as
% marrow fat = % dry weight – 7 Brooks et al. 1977; Pole et al. 2004
|Determining physiological aspects of study animals
Collection of scat for faecal hormone analysis:
Faecal hormone analysis is used to answer specific research questions pertaining to physiology and histology. Unless monitoring goals aim to investigate these aspects, faecal hormone analysis is not relevant to population management.
Determining levels of adrenal glucocorticoid secretion can be very useful when investigating behavioural interaction and responses between pack members. An increase in glucocorticoid levels occurs in response to a stressful situation, allowing direction of energy towards resolving the situation. If the stressor is not eliminated the glucocorticoid levels will remain high resulting in negative physiological consequences such as immune suppression, loss of muscle and reproductive repression.
It is very important to collect and store faecal samples to be analysed in the correct way. When collecting faecal samples, a note of which individual deposited the scat should be made so that the hormonal response can be directly linked to the observed behaviour. Approximately 5 ml of freshly deposited scat should be collected and placed immediately into a cooler box and then transferred to a freezing facility as soon as possible. All samples should be carefully labelled with the identification of the defecator, time of defecation, time of collection and GPS location of where the sample was collected. Samples, labelled with the researchers name and contact details can then be sent to a laboratory for analysis.
For more details on glucocorticoid levels and how to get them analysed contact; Department of Production Animal Studies at Onderstepoort
Tel: +27 (0)12 5298216
Collection of scat to assess endoparasite load:
A high parasite load can be an indication of deterioration in health of a wild dog. Load of gastrointestinal parasites can be determined through the collection and inspection of scat samples. A standard sample of the whole scat should be collected (i.e. the same amount each time) and preserved immediately in 10% formalin for microscopic screening. These formalized faecal samples can be examined macroscopically (with the naked eye) for the detection of proglottids and adult helminths and then microscopically to detect eggs and cysts (See Henriksen and Christensen 1992 for more detailed methods).
Necropsy and collection of samples from deceased wild dogs:
Necropsies or post-mortems of deceased wild dogs, to collect tissue samples, are important to screen for disease and provide baseline data on normal, disease-free tissue to biological resource databanks. For a detailed description of how to perform a necropsy, safety measures to be taken and how to store and transport samples to Table 12.2. and Box 12.1. on pages 249 – 251 of the IUCN’s Status Survey and Conservation Action Plan for Canids Report (pdf) click