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December 2021 Bird Banding Expedition

December 30, 2021

Usually Reserva Las Tangaras is a quiet place. At lower altitudes the dominant sound is the rushing of the river, while up on the trails the buzzing of insects and croaking of frogs provide a constant but soft white noise broken only by the occasional raucous mixed flock. This month was different. The quiet cabana and peaceful trails were bustling with the arrival of 13 visitors for the biannual Reserva Las Tangaras birding expedition. 

First to arrive were five Ecuadorians to help run the project: two men experienced in local bird ID, mist netting, and bird banding, two wonderful cooks, and their six-year-old daughter who never failed to entertain us with her drawings, card games, and questions about our favorite colors and animals. Next arrived an enthusiastic, bird-savvy group of volunteers from North America led by Dr. Dusti Becker, Co-Director of Life Net Nature and the Reserve’s owner. Over the next two weeks the group would conduct standardized surveys and mist net and band birds in order to assess avian community composition around the reserve and contribute to the long-term dataset from previous years’ expeditions. 

We jumped into work the very first day. After a classic Ecuadorian lunch of soup followed by rice and lentils, accompanied by fresh juice, we went outside to review the basics of mist netting and bird banding.  

So, as you might have guessed by this month’s topic, it’s Mary writing this month’s blog (yes, I know, yet another post about birds). However, as bird banding has been a primary aspect of all my jobs over the past few years, I was excited to use this month’s expedition as an opportunity to write a bit more about bird banding and its importance to avian research. But before we jump into how mist netting and bird banding are used in avian research, let’s review the basics: what even are mist netting and bird banding?

Mist nets are a tool commonly used in avian field research to safely catch birds. Similar to a giant volleyball net, a mist net consists of two upright poles with a large net strung between them. The fine mesh of the net is difficult to see so birds fly into it and become trapped in its pockets. Once in the net, birds can be safely removed and banded. Bird banding involves placing a small metal ring on a bird’s leg. The metal bands are extremely lightweight and sized and placed so as not to be painful or cumbersome to the bird. Each ring has a unique combination of numbers so that individual birds can be identified if they are recaptured in the future. Along with receiving a band on its leg, captured birds are often measured (weight, wing length, bill length, etc.), checked for breeding condition or ectoparasites, and in some studies feather or blood samples are taken.

Banding crew carrying net poles from one netting site to another. Although it was hard work carrying supplies on the steep trails between banding sites, we all stayed in high spirits. Photo by Erin Bell.

So great, now we’ve got a bird with a little metal band on its leg and we have some numbers representing the bird’s size, mass, and general body condition. However, given all the work involved in setting up and taking down mist nets (especially challenging on the muddy hills around Las Tangaras, as any of the volunteers would surely tell you!), extracting birds from nets, banding and measuring birds, and entering and managing data, what is the point of all this? Without a doubt, it’s an incredible experience to hold a bird in one’s hand and to see the wonderful details not visible from a distance. However, far beyond seeing pretty feathers up close, bird banding is a crucial tool in avian field research. Below are the primary ways in which bird banding is used in bird research:

  • It may seem obvious, but a main point of bird banding is to provide us with basic information about birds. With a bird in the hand, we can take various body measurements, feather and blood samples, and check for ectoparasites. It is important to know this basic information about a species in order to understand its anatomy and physiology. Furthermore, blood and feather samples can tell us about energy sources and relatedness of individuals, which is important for understanding social interactions and energy needs. 
Green-crowned Woodnymph in the hand. You can see the tiny band on its right foot! Photo by Erin Bell.
  • Another purpose of banding is to understand species distributions. Mist netting is a valuable tool for determining what species are present in a given area. It can be especially helpful for detecting species that are quiet and rarely seen, thus less likely to be detected with other survey methods. For example, during our two-week expedition we caught a Plain Xenops, a species we haven’t yet seen or heard during our 2.5 months at the reserve. By capturing the Plain Xenops in the nets, we know this species is present in the area surrounding the reserve. 
Volunteer Ana holding the Plain Xenops that made its way into our nets. Photo by Mary De Aquino.
  • Mist netting is also a great way to gather demographic data on bird populations. Recapturing a previously banded bird gives us information on how long birds of that species live. In addition, certain characteristics, such as plumage, skull development, and breeding condition, can help biologists determine a bird’s age and sex. Examining trends in age and sex ratios of a population can allow biologists to determine demographic trends and possible mechanisms of any changes. For example, if researchers have been collecting data at a given site for multiple years, they can determine a normal age ratio (number of juveniles compared to adult birds). Seeing changes in this ratio can give researchers an idea about where in birds’ life cycles these changes are taking place. Fewer juveniles can indicate a decline in reproductive success, which suggests more research conducted on the breeding grounds may reveal the cause of the decline. Fewer returning adults during spring migration may indicate problems on the species’ migratory route or wintering grounds. Such information can help researchers decide where to allocate research time and money. 
Volunteer Brandon holding an adult male Pale-eyed Thrush. This bird was aged and sexed based on plumage and breeding condition. Photo by Erin Bell.
  • Mist netting is also a helpful tool for bird tracking efforts. Recapturing a previously banded individual, either at the same banding station or another location, lets us know where a bird is during that time of year. Mist netting is also valuable as a way of capturing birds to put tracking devices on them. Tracking birds is especially valuable for conservation because it gives us information on where a species goes during its full annual cycle. This is important for preserving habitat throughout a species’ range.
Bay-headed Tanager in the hand. Photo by Mary De Aquino.
  • Finally, bird banding is valuable as an educational tool. While seeing birds in their natural habitat is a great way to foster in people an interest in birds and the environment, seeing birds up close is a wonderful opportunity to educate people about aspects of bird anatomy that are not so easily seen from a distance. Seeing a bird in the hand, or getting the opportunity to hold and release a bird, can spark a whole new appreciation for these incredible feathered critters. From the beautiful details on individual feathers to marveling at how such a light animal can travel such huge distances, banding provides an opportunity to gain a new perspective on birds. Many banding stations are open to the public and provide a place for school field trips and scientists alike to learn about and appreciate birds and bird research. 
Banding instruction on the first day of the project. Photo by Aidan Sullivan.

Many of these valuable aspects are incorporated in the banding efforts at Las Tangaras. Through the Reserve’s research, we are collecting valuable biometric and demographic data on many tropical species. Not only do the Reserve’s banding efforts sample what species are present in the area around Las Tangaras, but by mist netting in different habitat types during the two-week project, we are sampling how avian community composition varies by habitat type. Capturing the same individuals multiple years in a row also gives us information on survival and site fidelity (that is, the likelihood of an individual to return to a previously occupied location). Finally, by incorporating volunteers, the banding project serves as an educational opportunity to teach people a valuable tool used in avian research. 

Volunteer Maureen with an Olive-striped Flycatcher. Photo by Erin Bell.

From setting up mist nets on the first afternoon to participating in the Mindo Christmas Bird Count on the final day, this year’s expedition was a great success. During the two-week project, we detected a whopping 183 species. Furthermore, we are grateful for all that we learned from both the volunteers and Ecuadorian staff. It is inspiring and heartwarming to know that there are such talented, passionate people working to preserve the planet’s biodiversity.

The whole team on the last day of the expedition. This year’s Christmas Bird Count shirt featured the Sunbittern, a species we were lucky to see several times during the project.

The Reserve is quiet again. The sound of chopping from the kitchen and conversation from the front porch have been replaced by katydids in the lawn and Three-striped Warblers in the bushes around the cabana. But some reminders of this December’s project remain. We frequently see banded birds around the cabin. Perhaps they will be caught in July during the next banding expedition, contributing just a bit more data to the long term dataset here at RLT. 

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