Mist nets are used by ornithologists

Ornithology

Ornithology is a branch of zoology that concerns the study of birds. Several aspects of ornithology differ from related disciplines, due partly to the high visibility and the aesthetic appeal of birds...

 and bat biologists to capture wild bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s and bat

Bat

Bats are mammals of the order Chiroptera "hand" and pteron "wing") whose forelimbs form webbed wings, making them the only mammals naturally capable of true and sustained flight. By contrast, other mammals said to fly, such as flying squirrels, gliding possums, and colugos, glide rather than fly,...

s for banding

Bird ringing

Bird ringing or bird banding is a technique used in the study of wild birds, by attaching a small, individually numbered, metal or plastic tag to their legs or wings, so that various aspects of the bird's life can be studied by the ability to re-find the same individual later...

 or other research projects. Mist nets are typically made of nylon

Nylon

Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...

 mesh suspended between two poles, resembling an oversized volleyball

Volleyball

Volleyball is a team sport in which two teams of six players are separated by a net. Each team tries to score points by grounding a ball on the other team's court under organized rules.The complete rules are extensive...

 net. When properly deployed, the nets are virtually invisible. The grid size of the mesh netting varies according to the size of the species targeted for capture. Net dimensions are approximately 1–2 m high by 6–15 m long.
If used by trained personnel, mist netting is an efficient method of capturing flying animals, and accomplishing this with a low risk of incidental injury. In the United States, federal and state permits are required to capture wild animals with mist nets.

Despite mist net's common usage very little research had been done into their effects on their relative safety. A recent article found them to be a low cause of injury while providing high scientific value.

A dho-gaza is a type of mist net used for larger birds, such as raptors

Bird of prey

Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....

.

Specific Uses

Mist netting is a popular and important tool for monitoring species population, which includes assessing species composition, relative abundance, population size, and demography. Although setting up mist nets is time consuming and requires certification, there are certain advantages it has over visual and aural monitoring techniques, such as sampling species that may be poorly detected in other ways. Other advantages include easy standardization, hands-on examination, and prevention of potential misidentification of bird species by people. Because they allow scientists to examine species up close, mist nets are often used in mark-recapture studies over extended periods of time to detect trends in population indices (Dunn and Ralph 2004).

Specific uses of mist nets are:

•Mark-recapture for population sampling

•Humane capture and relocation of small birds or bats in industrial areas, such as malls, warehouses, plant nurseries, etc.

•Tagging and tracking

•Testing the health of bird or bat species


Because there is still debate as to whether or not these techniques provide precise data measurements, it is suggested that mist netting is used as a supplement to aural and visual methods of observation. One of the main disadvantages of mist nets is that the numbers captured may only represent a proportion of the true population size (Dunn and Ralph 2004). Mist netting is a unique method in that it provides demographic estimates throughout all seasons, and offers valuable guides to relative abundance of certain species or birds and/or bats (Dunn and Ralph 2004).

Example Study

Mist-nets can be important tools for collecting data to reveal critical ecological conditions in a
variety of situations. This summarized study, "Effects of forest fragmentation on Amazonian understory bird communities" by Richard O. Bierregaard and Thomas E. Lovejoy, used mist-nets to analyze the effects of forest fragmentation on understory bird communities in terra firme forest of Central Amazon.

Data from intensive mist-netting mark-recapture programs on understory birds from isolated forest reserves were compared to pre-isolation data from the same reserves to investigate changes related to isolation from continuous forest (Bierregard and Lovejoy 1989). Birds surveyed were from a variety of ecological guilds, including nectivores, insectivores, frugivores, obligatory army ant followers, forest edge specialists and flocking species. The periodic sampling by mist-netting capture program provided the quantitative basis for this project. Reserves of varied sizes (1 and 10 hectare) within the Biological Dynamics of Forest Fragments project site were sampled with transects of tethered mist-nets once every three or four weeks. Capture rates from isolated reserves were compared to pre-isolation rates to measure changes in population size and/or avian activity due to isolation (Bierregard and Lovejoy 1989). Data was analyzed in the following ways: capture rates per net hour as a function off time since isolation, percent recapture as a function of time since isolation, abundance distribution of species against the species rank by abundance, percent individuals banded according to species and feeding strategy, and finally, capture rates per net hour in isolated reserves against capture rates per net hour in continuous forests. A summary of the results and discussion as stated by Bierregaard and Lovejoy is as follows:

Indented line “...changes in the understory avian community in isolated patches. Following isolation, capture rates increase significantly as birds fleeing the felled forest entered new forest fragments. Movement to and from the reserve is limited as witnessed by an increase in recapture percentages following isolation. Species of birds that are obligate army ant followers disappeared at the time the surrounding habitat was removed from 1 and 10 ha areas. The complex mixed-species of insectivorous flocks typical of Amazonian forests deteriorated within 2 years of isolation of 1 and 10 ha forest fragments. Several species of mid-story insectivores changed their foraging behavior after isolation of small forest reserves.”

All of this data was collected using mist-nets, and gave way to these different dimensions of information about the understory bird community at this site. Data such as this can be extrapolated to gain understanding of ecological effects of factors impacting ecosystems, such human activities or environmental changes. This is just one example of the use of mist-nets as a tool for ecological and biological sciences, as well as possible ecosystem management implications mist-net data offers.

Disadvantages

There are several disadvantages to using mist nets. Mist nets are very time consuming. They have to be set up properly without mistakes. An animal caught in a mist net can become entangled, so the net must be checked often and the animal removed promptly. Disentangling an animal from a mist net can be difficult and must be done carefully by trained personnel. If an animal is heavily tangled the mist net may need to be cut to avoid injuring the animal which ruins the net as well. Also, sometimes a mist net can be inaccurate by completely under sampling the population size or even miss a species. This is due to the fact that some animals can escape from the net before the mist net user finds them inside of it. Sometimes, a particular species can appear in the mist net often because they are easy to catch or the species enjoys being caught for various reasons such as protection or an easy way to catch prey. This causes an error in the calculation of the amount of species in the given area.

Using mist nets can be risky since there is a possibility that the birds caught in the net can become harmed in the process. The average rate of injury for birds in mist nets is between 0 and 0.59% while the average mortality rate is between 0 and 0.23% (Spotswood et al. 2011). Larger birds tend to be more prone to leg injuries and internal bleeding while smaller birds usually have tangling issues and wing injuries. Factors that affect the injury and mortality rate are human error while handling the species, time of year caught, time of day caught, predators in the area, and size/material of the mist net.

Banders

Humans that deal with the species caught in mist nets are called banders. Banders are responsible for banding the species caught in the net so they can be tracked. In order to band a bird, one must have a banding permit. Banding permits are given to people who have gone through training and whose projects contribute to the conservation and management of the bird population. Banders are responsible for the animals caught and thus apply their training by paying attention to stress cues such as panting, tiredness, closing of eyes, and raising of feathers. If not, the animal can severely injure itself. There are different types of banding permits, the Master Permit and the Sub permit. Master Permits are given to individuals who band on their own. Sub permits are given to individuals who will be supervised while banding by a person with a Master Permit. In order to receive a permit, one must fill out an application and return it to the nearest banding office. Banders must ask for special authorization in their application in order to use mist nets, cannon nets, chemicals, or auxiliary markers (North American Bander’s Study Guide 6).

External links

• North American Banding Council