​The Rufous-vented Ground-Cuckoo (Neomorphus geoffroyi) is a vulnerable species within the neotropical ground-cuckoos (Neomorphinae), whose foraging ecology and life history details are little known. Previous reports have shown that ground-cuckoos associate with several types of interspecific foraging groups including primates, peccaries, and army ants. Our observations indicate that ground-cuckoos also occasionally associate with understory mixed-species flocks. These flocks are a common feature of the moist tropical forests where ground-cuckoos are found. These flocks provide much of the apparent benefits of other foraging groups, in that they act as “beaters” that flush insect prey, as well as providing alarm calls that alert flock members of predators. Further, mixed-species flock territories saturate forest of suitable habitat, and they can maintain territories for multiple decades. These may provide a predictable source of foraging benefits for ground-cuckoos.

Photo of Neomorphus individual from video 1 at Pantiacolla in September 2015. Photo Cred. E. Parra

In our first observation, we document the attack-strike foraging behavior (< 1 second) of N. geoffroyi in attendance of a mixed-species flock and an ant swarm. Our second and third observations show N. geoffroyi associating with mixed-species understory flocks away from ants. We suggest that N. geoffroyi may be a generalist follower of interspecific-groups that disturb prey. Their robust body size and associative foraging strategy may help explain their large territory sizes and low density. 

Figure 1. (A) Frame from video of observation 1 showing the head and neck of the ground cuckoo, filmed at the Pantiacolla Lodge. (B) Frame from video from observation 2 showing the upper body of the ground cuckoo, filmed at the Cocha Cashu Biological Station. (B, inset) Spectrogram of the calls of the individual shown in the photo. (C1-C3) Frames illustrating the attack behavior of the Rufous-vented Ground-Cuckoo, including the time (beginning at 000 milliseconds (ms)), target leaf location (yellow dot), and a circle tracking the cuckoos head location in each photo frame.

Video 1, filmed at Pantiacolla field station in September 2015. Neomorphus individual is seen foraging with mixed-flock over a group of army ants.

Video 2. Filmed at the Cocha Cashu field station in Semptember 2018. Neomorphus individual is observed foraging in mixed flock before being filmed. Individual responds to the imitation by author of its coo-ing call (fig 1) by hopping onto a low branch and calling back.