Appearance and Identification:
Black-capped Chickadees (Poecile atricapillus) are well-known songbirds, loved by everyone due to their adorable appearance and curiosity. They have a distinctive black cap and bib, contrasting with their white cheeks. Their sides are buff colored and the feathers of the wings and the tail are gray with paler edges. They molt every year in late summer, after their breeding season. Visually, it is extremely difficult to identify the sex and age of the chickadees since there are no distinctive features differentiating them. They have an average length of 5 ¼ inches with a wingspan from 6 to 8 inches (5). Black-capped Chickadees use a variety of distinctive calls (fee-bee, chick-a-dee, seet), depending on their intentions (alarms, courtships, etc.) and certain acoustic features in the “fee” part of a call allows us to distinguish between male and female calls (2).
The most common place for Black-capped Chickadees to nest is inside cavities of rotten trees dug by them or abandoned by woodpeckers or other birds. When digging their own nest hole, they will scatter the wood chips away from the site to avoid attracting predators. The female is the one in charge of building the nest and uses rabbit fur or soft plant fibers for cushioning (5). She will then lay one egg per day until there are about 6 to 8 eggs. The young hatch after 13 to 14 days and will leave the nest 16 to 17 days after hatching (1).
Black-capped Chickadees are widely distributed throughout North America, being found just below the Arctic all the way to the mid United-States stretching from the Pacific to the Atlantic coast (5). Due to this, the birds make use of many different habitats such as mixed and deciduous woods, thickets, and willow groves. Given suitable nesting areas, they can even be found in urban areas (1). The Black-capped Chickadees are non-migratory birds due their weak flight (5). Despite their weak flight, every few years when there is a large increase in population immature chickadees will fly south for the winter and return north in the fall in a phenomenon known as “irruption”(5).
Black-capped Chickadees are omnivorous birds whose diet includes insects, berries, and seeds (1). As they do not migrate, the exact content of what they eat varies depending on seasonal availability. Since feeders provide an easy source of food, it is common to see them flock to feeders, but they won’t stay on the feeder long. Chickadees seldom eat on the spot and instead either fly to safety to eat or store their food (called caching) (5). The seeds are stored in various locations to prevent drastic losses if another bird was to find a cache and chickadees have demonstrated an amazing ability to recall these locations (3,5). If the chickadees decide to eat the seeds rather than cache them for later, they often fly away with a seed to a covered branch before holding it with their feet and pecking at it.
video: To eat, Black-capped Chickadees hold the seed with their feet and peck at it with their beak until it breaks open. You can also hear the characteristic “chicka-dee-dee” call they make, where the number of “dees” in the call increases when they feel threatened
Despite their tendency to travel in noisy parties, the friendly Black-capped Chickadee is very choosy about when and with whom it will eat. Upon observing chickadees at a bird feeder, we noticed that they don’t like feeding at the same time as other birds, whether of their own or another species. They patiently wait until one bird has flown away before taking their turn. The weather also influences chickadee’s foraging; on cold, windy days they forage lower to the ground in more dense foliage to block the wind (5).
Video: Chickadees often wait their turn at feeders. It is rare to see two birds, of the same or different species, on the same side of the feeder at the same time. (other bird featured: White-Breasted Nuthatch)
An interesting study done on anti-predator behaviour in Black-capped Chickadees showed that the birds will trade off foraging for safety. After being exposed to a simulated predator, fewer birds visit the food patch and they take longer to come out of hiding to get more food, especially when the patch is further away from their refuge (6). It’s possible to tell when a chickadee is in peril simply by noting the amount of “dees” in their famous “chick-a-dee” call. The more “dees” heard the higher level of threat present (4). It turns out that higher ranked chickadees are leaner than lower ranked individuals, and therefore are more manoeuvrable in the face of predators. That’s not their only advantage; females will select males of higher rank to mate with before considering their subordinates (3). Chickadees become more quiet and inconspicuous during their summer mating season, which is very different from the behaviour we see in the fall (5).
Their non-migratory way of life and stable presence at the Morgan Arboretum makes Black-capped Chickadees the perfect study species for our research. The ease with which they adapt to humans was also key in helping us develop our research question: Does human presence and activity in certain areas of the Morgan Arboretum influence Black-capped Chickadee abundance and behaviour?
With this question guiding us, we used visual and auditory cues to survey six sites in the Morgan Arboretum. The six sites included three sites with lots of human activity off a hiking trail used year round, and the other three were off a snowshoe trail with very little human activity this time of year. Auditory cues were relied on most, and the spacing and direction of calls were used to distinguish if we were hearing one or multiple individuals. If the calls were spaced out and from different directions, they were counted as coming from different individuals, whereas calls that were less spaced and from the same area were counted as one individual. To survey the sites, we split into two groups of two and took different routes in order to obtain more observations of the sites at different times. Once we arrived at a site, we waited five minutes before recording observations so the area was less disturbed. After the five minutes, we recorded abundances as well as behaviours for fifteen minutes. From our three days of data collection we noticed that chickadees do seem to be more abundant in the high human activity sites.
(1) Foote, J.R; Mennill, D.J; Ratcliffe, L.M; Smith, S.M. 2010. Black-capped Chickadee (Poecile atricapillus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; [cited 2015 Oct 27]. Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/039 doi:10.2173/bna.39
(2) Hahn, A.H; Hoang, J; McMillan, N; Campbell, N; Congdon, J; Sturdy, C.B. 2015. Biological salience influences performance and acoustic mechanisms for the discrimination of male and female songs. Animal Behaviour, 104, 213-228.
(3) Otter, K.A. 2007. Ecology and Behaviour of Chickadees and Titmice: an integrated approach. New York: Oxford University Press.
(4) Schwarz, J; Greene, E; Davis, K. 2005. Chickadees’ alarm-calls carry information about size, threat of predator. University of Washington.
(5) Smith, S.M. 1997. Wild bird guides: Black-capped Chickadee. 1st edn. Hong-Kong: Stackpole Books.
(6) Turney, S; Godin, J.G.J. 2014. To forage or hide? Threat-sensitive foraging behaviour in wild, non-reproductive passerine birds. Current Zoology, 60, 719-728.