I am going to start a breeding study for ground-nesting birds in a low-grass steppe and I could use some advice in how to mark the nests found in order to easily locate them in next visits, and thinking about not to attract predators and not to modify the surroundings too much.
GPS will be used but usually accuracy is 5m or less.
Thanks!
Dear Martin, we've worked on non-steppe birds i.e. waterfowl and waders, but often they nested in short-grass meadow areas. It seems to be a good method to set thin tree sticks being like natural local plants but somewhat unlike plants growing there in their height (i.e. be not thicker, and in the same time taller) at distance in several meters from the nest in a definite bearing, for example, always in 5.00 meter to the north. Indeed, working with it you need a good compass and a tape-measure. Instead the north, you can use some reference objects like stones, trees, etc. so that the nest would be in five meters from the stick in the direction to the tree/stone. - but if only such objects are present around, and if you know exactly which reference object does for each nest! A stick should be as thin as to don't let raptors to perch on and to don't let cows (if present) to be attracted and scratch their flanks about the stick.
Indeed, there are technical methods, which let to define the nest position more precisely, e.g. radio tags etc, but they are much more expensive for use.
You need to specify the map of the geographical location and the ground area so that you can start locating your place of work
Then you select the existing signs or trees or put the signs yourself and record the measurements of each nest away from the mark that you selected and so on.
Avoid nuisance the birds or work when they leave their nests
I have often used flagging and a compass and a nest card with explicit directions (e.g., "10m from flagging @ 350 degrees, just to left of small red rock". You are right to be concerned about predators but if you use a small strip of an indiscreetly colored flagging and vary the distance and direction to the nest (never putting the flagging right on a nest) you will minimize that risk. I like the idea of the stick (and related caveats) that is presented above.
Martin, here is a paper that might be of interest to you. It includes recommendations for locating and marking grassland bird nests:
Winter, M., S. E. Hawks, J. A. Shaffer, and D. H. Johnson. Guidelines for finding nests of passerine birds in tallgrass prairie. Prairie Naturalist 35:197-211. http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1159&context=usgsnpwrc
Thank you for all your answers! I will make a first attempt marking with small flags at 2 - 3 m from nest always in the same direction, to test if that signal can stand on foot during the whole reproductive cycle.
If you have access to VHF telemetry equipment, you can place a transmitter near the nest. We did that for many years with Greater and Lesser Prairie-Chickens, using old transmitters, consistently placed 2 meters due north of the next. Since the hen was also radioed, we could monitor the nest remotely by checking her frequency and the "marker radio" frequency, and confirm whether she was on the next, then use the "marker radio" to relocate the nest after it hatched or failed.
If you want to get away from using flagging or other unnatural markers that might attract predators, you can make a small pile of rocks X meters (or paces) from the nest. Take a GPS point of the marker and detailed notes on where the nest is from there. Can also leave space on the data sheet for a small sketch. This is how we monitored Greater Prairie Chickens in Kansas.
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