This study looked at the feeding patterns of a fruit-eating tropical bird, Blue-throated Toucanet (Aulacorhynchus caeruleogularis) in shade coffee farms in the Monteverde region of Costa Rica.
Blue-throated Toucanets were once considered a subspecies of Emerald Toucanet, which was featured in the Know Your Coffee Birds series here on C&C. The goal was to determine how fruit resources – in particular the reliability of fruit energy throughout the year – influenced the persistence of fruit-eating birds in agroforestry systems like shade coffee.
Finca La Bella is a group of 24 independently owned small farms that grow coffee under a high diversity of shade (unlike much of Costa Rican coffee). Around 20 different tree species per ha are used for shade here, but different farms may have different types of shade trees. The authors looked at the types of fruit growing on six of the organic farms, and measured the fruit calories available to birds over most of the year.
Researchers found that the toucanets were located 20-30% more often on farms that were considered to have “high fruit security.” These were farms on which the fruit energy available was greater than 1000 calories for four months or more. This calorie threshold has been found in other studies to be the point at which more birds immigrate into a farm rather than leave to find food resources elsewhere. The home range of toucanets was also found to be smaller on farms with high fruit security, indicating the birds did not have to roam as far to find the fruit they needed.
Although Blue-throated Toucanets have been observed eating many dozens of types of fruits, some are preferred over others. The fig Ficus pertusa accounted for 69% of all observations in this study. The fruits of the familiar Cecropia (Cecropia obtusifolia) and of Firebush (Hamelia patens) were also important.
The authors concluded that to improve the quality of the agroforestry systems for fruit-eating birds, the type of trees used for shade or preserved on the property should be taken into account, including the year-round availability of fruit resources. Ficus were especially important in this study.
Aside from the preservation of biodiversity, fruit-eating birds perform the critical service of seed dispersal in tropical forests. Therefore, managing shade coffee farms to benefit these birds is of high conservation value.
Peters, V., & Nibbelink, N. 2011. The value of fruit security for the conservation of a neotropical frugivore in human-dominated landscapes Biodiversity and Conservation, 20 (9), 2041-2055 DOI: 10.1007/s10531-011-0073-5
Blue-throated Toucanet photo by Scott Ableman under a Creative Commons license.