Mist netting is a nice methodology for assessing flying wildlife, especially birds and bats. The outcomes of the mist netting can be used in a wide variety of activities, including migratory surveys, population census, health/viability of given populations, conservation studies and so on.
Mist nets generally consists in a wall of thin line with the aim of capturing birds or bats while they are flying. Beyond that, this big wall has smaller divisions called ‘shelf’ which are fundamental parts of the net where the animal will stay caught (it is so for the specimens don’t get to tangled in the lines and also lessens the harm and stress inflicted to them) until the responsible scientist comes to release it from the trap in order to collect all the possible data (not only the data he needs for a particular study, but all the information that can be extracted from the animal so it won’t need to be caught again and go through all the stress once more if the scientists decides to test another hypothesis). The length, height, line thickness and the spaces within the mesh can vary significantly, according to the focus prey and the environment where the study is going to happen. For an example, thicker lines are used more often to catch bats as they would chew thinner ones more easily; and smaller nets are ideal for areas where the vegetation is denser, so it don’t get stuck in the branches and become more conspicuous for the animals (and they won’t avoid it).
But only trapping the animals is not enough to gather all the information needed to activities cited before, we also need to individualize the animals and the most common methodology regarding birds is to band or tag them (but this second one is used only for big strong animals which are not captured by mist nets). Bird banding helps us to follow focal specimens and we can tell how are they doing over the time: if they are getting weight, if the population is declining or not, the sex ration of a given population, the adult-infant ratio and a huge variety of other important variables.
I am part of an ornithological laboratory within the Federal University of Rio Grande do Norte in the Northeast of Brazil. One of our major projects is conducted in the only Brazilian endemic biome, known as Caatinga and we use thin medium-sized mist nets for trapping birds and metal bands to identify and individualize them. And apart from being in the other side of the globe, I have done some field work here in Canberra (at the Botanic Gardens) and the methodology and material used are very similar: the nets are extended between wooden or aluminium poles tied with ropes to a tree or rock and observed by a safe distance (far enough to be hidden from the birds) until an animal hits the net. Another strategy to improve the mist netting success is to use playbacks for attract some birds. In my experience at the Botanic Gardens, we played the call of a target species which attracted only that species, reduced the impact of bycatch (it is pointless to capture a species that is not the focus of the study), and optimized the time spent on the field.
To sum up, mist netting is a useful and efficient technique which also improves our contact with the wildlife in a way that benefits both sides – improves our understanding of wild populations and makes it easier to conserve and protect them.
- Banks, J. E., Banks, H. T., Rinnovatore, K., & Jackson, C. M. (2015). Optimal sampling frequency and timing of threatened tropical bird populations: A modeling approach. Elsevier, 70–77.
- Desante, D. F., Burton, K. M., Saracco, J. F., & Walker, B. L. (1995). Productivity indices and survival rate estimates from MAPS, a continent-wide programme of constant-effort mist-netting in North America. Journal of Applied Statistics, 935-948.
- Maas, B., Tscharntke, T., Saleh, S., Putra, D. D., & Clough, Y. (2015). Avian species identity drives predation success in tropical cacao agroforestry. Journal of Aplied Ecology, 1-9.