Citizen science for understanding timing of bird migration in urban parks

Urbanization has been cited as one of the greatest threats to biodiversity. Nonetheless, species such as the austral migrant Myiodynastes maculatus solitarius (Streaked Flycatcher) uses green areas within the urban context as habitat. The main goal of this study was to verify differences in the migratory timing of that species in urban parks inserted in distinct contexts within São Paulo metropolitan area (SPMA). For this, we used data collected from the online platforms eBird and Wikiaves, where there are 3139 records between December 1988 and April 2016. Additionally, we installed autonomous recorders (Song Meter SM4, Wildlife Acoustics) and conducted searches using playback in five parks located in the SPMA between September 2016 and April 2017. Two parks that are more connected and with more than 900ha: Anhanguera Park and Cantareira State Park, and three parks that are relatively isolated and with less than 100ha: Carmo, Butantan Institute and Ecological Tietê. We found evidence that Streaked Flycatcher stays in small parks until 15 march before leaving for the wintering grounds, whereas it remains until 28 March in the larger parks. This indicates that the departure day and its migratory timing seem to be related to the size of its breeding areas, perhaps because individuals in smaller areas are under stronger pressure to migrate early. These results reinforce the importance of citizen science-based data in revealing patterns and answering questions about bird distribution and ecology.