The “popcorn” birds

Since the fall of 2013, the birds in the Biodôme tropical rainforest have been enjoying one of their best reproduction cycles. The bird collection in each of the Biodôme’s ecosystems is defined as a community evolving in a specific and relatively stable environment. The cycle of the seasons synchronizes and stimulates breeding behavior, and is primarily a function of the photoperiod (how long the birds are exposed to light each day) in the Laurentian maple forest, the Gulf of St. Lawrence and in the polar worlds. In the tropical rainforest, seasonal variations are much less striking, but another factor comes into play: the domino effect.

One parade attracts another

In recent years the Biodôme has made its tropical bird community more complex through a number of acquisitions, including the rufous-collared sparrow, with its characteristic song. One couple in this species was released into the ecosystem, while another was confined to an aviary for breeding purposes. One of the males would often sing, and the couple took to building a nest. We believe that the frequency and the intensity of the male’s singing probably influenced the other sparrow couple, which also started a reproduction cycle. Not only did these two couples produce five chicks, but the turquoise tanager couple also produced three chicks, and the opal-rumped tanager couple added two more. All that in the space of a few months…

Common species…but so interesting

These three species are well known to ornithologists who spend time in South America. The rufous-collared sparrow is a bird that’s very common in nature. Nevertheless, just four institutions in the world present the species, which has only ever reproduced at the Biodôme. As for tanagers, 29 institutions (two in Canada) present the turquoise tanager, and only eight (one in Canada), the opal-rumped tanager. The special feature of the Biodôme is not that it showcases rare species, but that it accommodates species in communities, where they evolve with other individuals, and not all by themselves or as a couple.

Reproduction under close scrutiny

Bird reproduction at the Biodôme is very similar to that observed in nature. Even though the turquoise tanager has successfully reproduced here a number of times, we currently have an even better opportunity to study parental care. Parents have built their nest very close to the visitor path, making it easier to track their behavior. Curiously, a number of individuals (as many as four) take part in feeding the two chicks. Experienced parents tolerate the participation of two other females belonging to their group. In nature, this species forms monospecific groups (several individuals of the same species), but we don’t know the content of the social ties that bind individuals. Observations made at the Biodôme lead us to believe that family ties foster the cohesiveness of the group, and that captivity increases participation in caring for chicks. According to our sources, this behavior would be present in a natural environment, but still hasn’t been studied much.

A better understanding through observation

The presence of a monospecific group in a bird community is probably unique in a zoological setting, and the Montréal Biodôme is the place to observe it. This last year has taught us a lot about the social relations of these tropical birds: we’ve observed how the structure of the group influences the survival of individuals, how the courtship activities of singing and nesting are imitated by other individuals and even other species, and how parental care is shared. We continue to examine and learn, so that we can provide even better accommodations for a community that helps make the Biodôme a place of discovery and excitement.