Distribution, population, food types, and adaptive strategy of Sooty-headed Bulbul [Pycnonotus aurigaster Aurigaster (Vieillot, 1818)] in the agricultural area of North Sulawesi

This study aims to assess the distribution of Sooty-headed Bulbul in several habitat types, its population density in agricultural habitats, types of feed, and the adaptive strategy of species so that they can survive and thrive in North Sulawesi. The research was conducted from March 2019 to September 2020 on the main island of North Sulawesi province. Species distribution survey was carried out in several types of habitats, including primary and secondary forests, mangroves, shrubs, forest edges, coconut plantations, teak plantations, seasonal crop agriculture (corn, cassava), bamboo groves, grasslands, rice fields, rural, and even urban areas. The surveys were conducted at 06.00-07.00 by inventorying the number of encounters with species during observation in that habitat typestyle. Plots were established in line transects 1000 m in length and 20 m in width. Observations were repeated three times. Encounter frequency from the average number of individuals during the survey was categorized into ++++ (>3), +++ (2-3), and + (<2). The density of individuals in agricultural areas was conducted through surveys with line transect plots 49,400 m long and 20 m wide. Food types were observed ad libitum by observing and identifying the types of food consumed by Sooty-headed Bulbul during the observation. The adaptive strategy of the Sooty-headed Bulbul was observed through interactions with other species and the level of resistance to human activities. The results showed that this species can be found in primary and secondary forest habitats, mangrove forests, shrubs, forest edges, coconut plantations, teak plantations, seasonal crop agriculture (corn, cassava), bamboo groves, grasslands, rice fields, rural areas, and even urban areas. Surveys in agricultural habitats found as many as 192 individuals/km2. Sooty-headed nightingales use a wide variety of food. The ability to adapt to various types of food is an important factor in maintaining and increasing its population. In North Sulawesi, many types of fruits, especially papaya and banana, are quite abundant in agriculture/plantations, thus providing a large source of food for the needs of this species. In their activities, Sooty-headed Bulbul often joins or forms alliances with other species that are found to be closely related to human activities. The results show that Sooty-headed Bulbul can utilize various types of habitats, and various types of food, and have adaptive strategies towards other species and proximity to human activities that allow them to survive and thrive in North Sulawesi.