Camera-trapping is difficult at the best of times, what with waving vegetation, birds and small rodents triggering cameras as well as cows scratching their bottoms on cam-trap emplacements. To add to this, we now have a Ninja badger who has taken great exception to our equipment at one site and attacks it with great panache!
This leads to an aspect of cam-trapping that is often overlooked when monitoring mammal activity; whether the act of putting up/maintaining cam traps, or the cam-traps themselves causes any disturbance to the target mammal. I have seen a few cam-trap monitoring reports, and often the cam-traps are left out for a few days, and there is no consideration of whether a period of habituation is required. There have been some studies on disturbance (Meek et al., 2014; Munoz et al., 2014) and it would appear that some species are more sensitive than others.
At our otter sites, the otters exhibit very chilled behaviour such as loafing and snoozing and don’t pay much attention to the cam-traps. I should qualify this in context of the IR illumination we use which is always “black” IR or covert IR. This is in contrast with the reaction to standard red IR, purported to be invisible to mammals. Needless to say that after seeing otter react to red IR, we always use, and advocate “black” IR.
However, all our sites are long-term study sites and at the end of the data collection period we plan to analyse whether there was any habituation.
Badger, however seems to exhibit much more awareness of camera-traps and will snuffle, scratch, sniff and snot over them on a regular basis. As it stands (in Scotland), you don’t need a licence for disturbance to cam-trap badger, but I think that the assumption that the badger is robust and not disturbed by cam-traps is more based on our perception of badger being bolshy rather than science.
Meek, P.D., Ballard, G.A., Fleming, P.J.S., Schaefer, M., Williams, W. & Falzon, G. (2014). Camera traps can be heard and seen by animals. PLoS One 9, 1–16.
Munoz, D., Kapfer, J. & Olfenbuttel, C. (2014). Do available products to mask human scent influence camera trap survey results? Wildlife Biol. 20, 246–252.