We had several samples losses of Barber pitfall traps in our Alpine sites due to marmots that were attracted by the conserving solutions or trampling cattle. We used ethylene glycol, but we switched to the non-toxic propylene glycol, unfortunately both have a sweet taste, the latter with reported with less attractiveness.
I wanted to ask the community, if there are tips for metal cages that cover the pitfall traps.
I already designed some prototypes (I love to tinker :-) ) and ideally the cages should:
- not influence the catch pattern and rate
- be robust but also of light weight
- not be too expensive
Thank you,
Best, Michael
Dear Michael,
in my opinion, using cages is problematic, as you cannot know weather and how they influence trap catches - and most likely will have an effect on the catching rate of larger species. I would recommend using a non toxic non (or only little) attractive conserving solution (e.g. salted water - yet, sampling intervalls have to be small with this method) or just placing several replicates which are pooled later to overcome trap losses as proposed in Kotze et al. (2011). Best,
Fabian
Thank you Fabian for the info!
The cages I suggest to use will have noble mesh widths, so we hope that the influence regarding the environmental parameters and the catchment rate will be minimal as we focus on (soil) macrofauna / invertebrates - they should all pass without having problems.
We are working in Alpine managed grassland and here comes our big problem with salt: marmots, sheep and cows... I can tell you, sheep are really really really addicted to salt and they will do everything to get it :)
Skvarla MJ et al. 2014 reviews pitfall traps and preservatives, and after careful considerations, we tried propylene clycol, and found out that it preserves in a good way and is non-toxic, even when attraction has not been proofed yet (e.g. in the toxic ethylene glycol, the tissue of Lumbricidae desintegrate, no determination is possible then).
You see, we have to find a solution WITH cages, at least for quantitative approaches.
Thank you,
Michael
Hey Johannes,
thank you for the tips and you information!
I love the idea of flat cages, as this would reduce the weight for transportation. You know, we work in high alpine space, and saving weight is desirable for the long hikes :) I think they should have 5cm at least, as flat surfaces in alpine pastures are rare.
Unfortunately, we cannot use barbed wire... we tried it once and had big problems with the owner of the sheep and cows... animal welfare organizations don't like it neither.
We already talked with Erwin Meyer, but I will consider Rüdiger and Timo too, thank you for mention them.
We will see what we will and can apply in this season!
Best, Michael
Make any pitfall solution (antifreeze, saltwater) distasteful to mammals by adding a little formalin (not enough to harm insect integument for short periods).
Peter W. Messer (http://bugguide.net/user/view/12327)
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