As part of our BioBlitz preparations at the end of the last phase, a group of GVI Amazon volunteers (myself included) assisted Lana – the avian field staff member – in setting up a canopy mist net to try and catch different bird species.
A mist net is somewhat similar to a badminton net, made of very fine strands and multiple layers, each with pockets to gently hold birds that have flown into the net. Nets are checked at regular intervals and captured birds are carefully removed, identified, measured and then released. Normal mist nets are about 3m high; the idea with the canopy net is to string the net high up in the trees to study canopy-dwelling species. After a few practice set-ups around base (the technique is a VERY complicated system of rope and pulleys), we set off to the road to find a suitable location, somewhere with two trees of equal heights with clear space in between to put the net up. Using an adapted methodology from a paper published in the 1960’s, we got our two hoist lines over some pretty high branches by a slow process of shooting a sock filled with sand up into the trees until we finally achieved our goal. Once these were up we could build the rope frame that would enable us to move the net up and down in order to get the birds out and all of this used a series of metal loops to hold it in place. After a long day we set off back to base, looking forward to trying it out the next day.
|Our rolled-up canopy mist net up in the trees, soon to be unfurled |
(note the black line stretched across, marked with arrows)
However, as with many science experiments, not everything goes as one would expect. The main problem we encountered was that at this height, it was difficult to keep tension in the net. We attempted to fix this using the limited resources we have at base. Six poles, some duck tape and some string later, we had a net that was tight enough that our catch would not see the net and also stay in the net once caught.
Having fixed our first issue, we reset the nets but unfortunately, we were thwarted again – despite our efforts at improvements we couldn’t move the net high enough to catch the toucans that seemed to live directly in our net vicinity! Instead, not wanting our hard work to go to waste, we decided to try and catch bats in the hopes of adding something new to the species list. This would also give us an opportunity to get an up-close look at these elusive creatures that normally just speed past our heads.
We are still hopeful for toucans in the net someday soon, but until then we are satisfied with the large fruit bat that chewed a hole in the net!
Lois Mayhew – GVI Amazon Long-term Conservation Intern