The black-tufted-ear marmoset (Callithrix penicillata) mainly feeds on plant exudates which can comprise up to 70% of the diet (Miranda and Faria, 2001). Other items included in the diet are insects, nectar and flowers, in different proportions. Stevenson and Rylands (1988) classify marmosets from the Jacchus-group as exudativore-insectivores. It is known that marmosets opportunistically feed on protein sources i.e. prey, and that their small size allows for a quite diverse diet (Rylands and Faria, 1993). Insects are the most important source of protein, but other protein-rich food currently described for this species are ants, spiders, lizards, snails, frogs, eggs and bird hatchlings (Stevenson and Rylands, 1988; Passamani and Rylands, 2000). In this article, we report two new food sources, that may be included in the diet of wild marmosets, albeit probably very rarely: mouse and dove. We also report the ingestion of ants, confirming an animal food item in the diet of black-tufted-marmosets mentioned in the literature. Observations on predation by marmosets were made opportunistically when researchers observed the social behavior of two marmosets groups at two different study sites. Both sites, the Estação Ciência São Jose (ECSJ) and the Jardim Botânico de Brasilia (JBB), include many vegetation types of the Cerrado biome. The observations were in the cerradão, a typical forest with medium to high semi-deciduous trees and xeromorphic vegetation (Ratter et al., 1997).
Predation on a dove (Columbina talpacoti)
The dove predation was observed in the ECSJ, a field station of the Catholic University of Goiás (16° 44′ 06″ S, 49° 2′ 48″ W; Goiânia, Brazil), close to the suburb of the city, on 15 March 2001. Around 08:00, a group of black-tuftedear marmoset moved toward the area around the field laboratory, staying at approximately 3 m height in small trees (Grevillea robusta). Suddenly, the marmoset group became very agitated. We succeeded in recording with a digital camera the moment when an adult male, located approximately 2 m above ground, captured a dove (C. talpacoti), immediately biting it into the head and starting to eat it (Figure 1). We did not observe the prey being shared with any other group member. The marmoset showed piloerection during the voracious consumption of the dove.
Predation on a mouse (Mus musculus)
The predation on a mouse happened in an area near the entrance of JBB (15° 55′ 58″ S, 47° 51′ 02″ W; Brasilia, DF, Brazil). On 20 November 2006, at 08:30 h, we saw the reproductive female of the group capturing a mouse while foraging in the forest understory, approximately 1.5 m above ground, and immediately biting of the head of the mouse (Figure 2). Although other group members, particularly infants, approached the female with characteristic submissive vocalizations, the female did not share the prey, dropping part of the carcass (mostly skin) on the ground.
Predation on ants (Labidus sp.)
The predation of the ants happened along a forest border of the JBB. On 23 August 2006, beginning at 11:15 we observed the marmosets descending to the forest understory above and ground close to a swarm of army ants, identified as Labidus (Ecitoninae, Formicidae) by Dr. C. R. F Brandão (Zoology Museum, São Paulo University). The marmosets caught and quickly ingested ants and did not seem to be intimidated by the ants' bites. This continued for approximately 3.5 hours. During this period, the whole group (15 animals) accompanied the swarm front, but among them, only two male adults and two juveniles fed on the ants.
Callithrix penicillata is widely distributed throughout the Cerrado (Stevenson and Rylands, 1988), one of the world's hot spots for biodiversity conservation (Myers et al., 2000). This species, like C. jacchus, is found in urbanized areas and has been successfully introduced in several regions (Cunha et al., 2006; Mendes Pontes and Soares, 2005; Miranda and Faria, 2001; Stevenson and Rylands, 1988; Vilela and Faria, 2004). It is presumed to have a flexible and opportunistic diet. Most data available on the diet of the marmosets and tamarins is focused on fruits and exudates, making it necessary to better describe and comprehend the role of prey in the behavioral ecology of Callitrichidae (Nickle & Heymann, 1996; Heymann et al., 2000). The predation of bird nests, mostly for obtaining eggs and hatchlings is well described (Marini and Melo, 1998; Mendes Pontes and Soares, 2005), but according to Stevenson and Rylands (1988), marmosets rarely feed on birds and hatchlings when in their natural habitat. The relevant literature has few reports on the predation of adult birds (Cunha et al., 2006), and the predation of this species of dove in particular has not been previously described. The bird preyed upon is commonly found in urban areas in Brazil (Sick, 1997). The contact from this bird with marmoset groups is presumably common in cities and their surrounding areas. The common mouse is an invasive species of the Brazilian fauna and is closely connected to human activity. The mouse predation reported here occurred in an area with pronounced human influence, and proximity to garbage cans. Newborn mice are used to complement the diet of marmosets kept in captivity (Coimbra-Filho, et al, 1981). However, this is the first description of an adult mouse predation by a marmoset in a wild environment.
Our observations on predation of the ant genus Labidus by black-tufted-ear marmoset are in line with recent observations of Melo Jr and Zara (2007) in the Cerrados and Atlantic Forest. Rylands and collaborators (1989) and Melo Jr and Zara (2007) have already described marmosets as predators of ants and insects that are displaced by the raiding ant swarms. Mendes Pontes and Soares (2005) also mention the presence of ants in the marmoset's diet. Although there is a relatively high abundance of this ant species in the woods of the JBB, predation is not commonly observed. While foraging to attain the dove and the mouse was notably an individual behavior, the ants and insects flushed by the ants were eaten while the whole group foraged, as described previously by Passamani and Rylands (2000). The predation on the mouse and the dove, although interesting from the point of view of flexibility in feeding habits, also adds a potential epidemiological link between the several diseases that are present in the region (i.e. zoonotic hemorrhagic fevers, Figueiredo, 2006) and the managing of wild marmosets in preservation areas with strong human influence. Doves and particularly mice are important agents for the dissemination of several pathogens (Pereira et al., 2001; Sick, 1997) that infect both human and non-human primates.
We are grateful to Rui Chaves Bozza Jr. for the help with the dove picture. We thank Dr. Carlos Roberto F. Brandão (Zoology Museum, São Paulo University) for the ant identification, Christian Hoffmann for kindly helping with the English translation, and Prof. Dr. Eckhard W. Heymann for editorial improvement of the manuscript.