Black-capped and mountain chickadees are sister species that typically occupy different habitats and are partitioned by elevation. Mountain chickadees prefer high elevation, coniferous forests while black-caps occupy lower elevation, deciduous forests. However, these two chickadee species appear to interbreed in disturbed habitats,such as urban areas, flood plains, and logging zones. We are interested in how disturbances disrupt established species barriers to promote hybridization between these sister species.
--Band and monitor local, wild populations of black-capped and mountain chickadees
--Take blood samples from individuals for genomic analyses
--Measure hybridization between black-capped and mountain chickadee populations in rural and urban areas
--Establish nest boxes to monitor chickadee breeding
What happens when a bird is banded? Birds are captured using mist-nets and carefully removed by trained individuals. Birds are then banded with a federal numerical metal band and several plastic color bands so that they can be individually identified. Next, we take a small blood sample (~1 drop) that will be used in genomic analyses. Finally, we take photos and body measurements, such as weight, bill size, wing size, etc. Birds are then released. In total, most birds are handled for less than ten minutes.
Why do we band birds? Data from the birds we band goes directly to the Federal Bird Banding Laboratory. This large, long-term data set from all over the country, on numerous bird species, enables researches to investigate bird dispersal and migration, behavior and social structure, life-span and survival rate, reproductive success and population growth. For the chickadee banding project, each bird gets a unique set of colored bracelets, which allows us to track individuals without re-capturing a bird.
Do the nets hurt birds? Birds are caught using fine-mesh nets called mist-nets. Birds are unable to see the nets and fly into them, where they are carefully extracted by trained professionals. Using data from 22 banding stations across the United States, Spotswood et al. 2012 determined that less than 1% of birds captured are injured or killed by mist nets. Becoming a permitted bander requires extensive training and all banders follow the Bander’s Code of Ethics. Under the Code of Ethics, a bird’s safety is researcher’s number one priority. Banders minimize the time bird spend in nets and in hand, carefully monitor weather conditions and individuals’ needs.
Do bands hurt birds or impact their flying abilities? Both the metal federal bands and plastic color bands are less than 0.5% of a bird’s weight. This weight is negligible and does not impact flying abilities. It is impossible to compare survivorship between marked and unmarked birds because unmarked birds cannot be individually identified, but there are numerous records of chickadees with 15 year lifespans following banding (Elder & Zimmerman 1983).
Does bleeding harm birds? We take blood samples from a bird by pricking the brachial vein. This is synonymous with finger pricking for blood sugar tests. We take 10 uL (0.01mL; roughly one drop) of blood, which is less than 1% of the bird’s body mass (Owen 2011). Bleeding does not reduce survivorship in chickadee populations (Smith 1995).
Citations and Additional Resources:
Elder, W. H., & Zimmerman, D. (1983). A comparison of recapture versus resighting data in a 15-year study of survivorship of the Black-capped Chickadee. Journal of Field Ornithology, 54(2), 138-145.
Owen, J. C. (2011). Collecting, processing, and storing avian blood: a review. Journal of Field Ornithology, 82(4), 339-354.
Smith, S. M. (1995). Age-specific survival in breeding black-capped chickadees (Parus atricapillus). The Auk, 840-846.
Spotswood, E. N., Goodman, K. R., Carlisle, J., Cormier, R. L., Humple, D. L., Rousseau, J., ... & Barton, G. G. (2012). How safe is mist netting? Evaluating the risk of injury and mortality to birds. Methods in ecology and evolution, 3(1), 29-38.