(In verband met internationale samenwerking zijn sommige van onze berichten in het Engels geschreven; excuses voor het ongemak)
Over the years the so-called Jiggler method has been developed and used by researchers of the Dutch Small Mustelid Foundation to make inventories and perform monitoring of mesocarnivores. This included foremost the following of regional population developments of the Pine marten (Martes martes) in the Netherlands (through the Dutch Pine Marten Working Group). The Jiggler-method is a versatile and proven method to record throat or ‘bib’ patterns (figure 3) for the individual recognition of trap happy Pine marten and Beech marten (M. foina). With the Jiggler we have also repeatedly recorded Otter, Polecat, Badger, Raccoon, Red fox, Genet and European wildcat. The Jiggler-method has also been successfully deployed by other nature research and conservation groups abroad, including from Ireland & The UK, Iran and Georgia (Caucasus).
Having worked with the Jiggler-method for more than eight years it became apparent that an improvement or new technique could take away some of the drawbacks of the Jiggler. These include a considerable amount of ‘noise’ from wood mice taking away the lure in a short time, limit in keeping freshness of the lure (usually a mix of salt-less peanut butter and food-grade fishoil) and offering a limited amount falling short for a longer monitoring (usually one week).
For the last two years we have been trialling the new T-predator ‘sniffer’ or ‘feeder’. This is simply a home-made device consisting of PVC plumbing tube (Ø = 4 cm; as purchased from a Dutch hardware store) cut to length 65 cm and fitted with a removable T‐junction on top (figure 1). The T‐junction functions as a reservoir for bait to serve several feeding (or conditioning) visits by mid‐sized animals. The reservoir in the T‐junction of the PVC tubing can contain a good reservoir of bait requiring some effort by the visiting animal to obtain all the bait over time; usually lasting around two weeks with repeated or longer feeding visits. A number of holes (Ø = 0,5 cm) are randomly drilled in the top end of the PVC‐pipe and in the T‐junction
to allow for optimal dissipation of the smell of the lure by wind current. The bottom-end is sawn off at an angle to allow for sticking it into hard soil.
The T-junction can be filled with a lure like peanut butter combined with fish oil, but can also hold a sachet (we use plastic fly scree cloth) with a certain (wet or dry) lure; for example Valerian for attraction of cats or cotton wool with other scent (e.g. Chanel No. 5 as attractant for a broad spectrum of animals). The use of meat is not advised in summer conditions, as this will quickly decay under warm conditions and attract flies and carrion beetles. A ‘closed system’, allowing only a lure function (without feeding) with food stuffs can be applied by using a tightly fitting cap instead of a T-junction.
The T-feeder or sniffer set‐up is non-harmful to subjects and allows for a durable fresh offering of bait during dry and raining conditions.
The T‐sniffer has proven to attract a wide range of mammals, in particular mesocarnivores (figure 2). Although not yet compared in an experimental set-up, preliminary results indicate that the T-model works considerably better and more consistently in attracting animals like pine martens to a camera trap station. Although more obstructive and a little less versatile than the Jiggler, the T-sniffer also allows the effective recording of bib patterns in pine and stone martens.
The use of T-model predator sniffer and feeder – designed by ecologist Erwin van Maanen – is open source, and use in conservation studies is warmly encouraged. We welcome your feedback and experiences.