The olive-sided flycatcher (Contopus cooperi) is a small to medium sized passerine bird in the family Tyrannidae, the Tyrant flycatcher family. It is a migratory species that travels from South to North America to breed during the summer. It is a very agile flyer and mainly consumes flying insects on flight. Since 2016, this species has been assessed as being near-threatened globally (IUCN) and threatened in Canada (SRA) due to its declining populations. Olive-sided flycatchers are migratory songbirds which are relatively small. It is qualified as small to medium-sized birds and are estimated to be smaller than American robins, but bigger than sparrows. The olive-sided flycatcher can be identified by its olive-grey or grey-brownish plumage above and with a white mid-breast section and throat. The olive tones on its back and wings are seen mainly in optimal light and when the feathers are freshly moulted. The sides of the breast area are grey and make the bird look like it is wearing a vest (see Fig. 2). It has a relatively long bill and long wings for its size. Sometimes, some of its head feathers can be raised which make it look like it has a small crest. The species does not exhibit sexual dimorphism, which means that male and female look similar. Olive-sided flycatchers perch in upright positions on top of dead branches or trees. (Source: Wikipedia.org, CC BY-SA)