The Wilson Journal of Ornithology 124 ( 2 ): 338 - 344 , 2012 
PREDATION ON SEEDS OF INVASIVE LA NT AN A CAMARA BY 
DARWIN’S FINCHES IN THE GALAPAGOS ISLANDS 
JORGE CARRI 6 N-TACURI , 14 REGINA BERJANO, 1 GIOVANNY GUERRERO, 2 
ENRIQUE FIGUEROA. 1 ALAN TYE,' AND JESUS M. CASTILLO 1 
ABSTRACT. Observations on birds feeding on fruits of the invasive shrub Lantana camera (Supirrosal were 
conducted on Santa Cruz Island. Galapagos (Ecuador) in the Dry Zone during the 2009 dry season. The endemic ground 
finches Geospizt i magnirostris (Large Ground Finch) and G. forth (Medium Ground Finch) were recorded eating Loam 
seeds w ith G. fortis the main consumer (>90% of records). Both finch species crushed the seeds and ate the embryos, 
discarding the exocarp and empty seed coats. They also dropped entire fruits to the ground, which could contribute to >hon- 
distance dispersal, but both finches also consumed fruits of L. camera on the ground. Density of L camera seedlings under 
aduli plants was higher in rockier areas than in bare soil since seeds were less accessible to predators and/or found more 
suitable irucrosites lor germination and establishment. Both species of finches serve as short-distance dispersers, hut rnainlv 
as seed predators of L, camera fruits. Received S July 2011. Accepted 15 November 2011 
The introduction, spread, and subsequent inva¬ 
sion ot alien species has become a problem 
worldwide, but is of particular concern on oceanic 
islands (Vitousek el al. 1997, Dulloo et al. 2002, 
Kueffer et al. 2010). The geographic isolation of 
islands limits immigration of new species while 
those that arrive subsequently evolve with fewer 
competitors and predators. The accelerated intro¬ 
duction of new species by people alters the natural 
ecological equilibrium of islands and can exert 
severe pressure on native species biodiversity 
(MacArthur and Wilson 1967). 
Frugivorous animals, by acting as seed vectors, 
have an essential role in the reproductive cycle of 
their food plants (Herrera 1995). Disperser avail¬ 
ability may be an important factor affecting 
invasion success, and alien plants arriving in new 
habitats have no guarantee of finding suitable 
dispersal agents ( Parker 2001). However. Richard¬ 
son et al. (2000) noted that invasive plants rarely 
sufter from a lack ol mutualistic services such as 
pollination and Jruit dispersal. Birds are recognized 
as the main dispersal agent of many invasive plant 
species around the world (e.g.. Dean and Milton 
2000. Renne et al. 2002. Gosper et al. 2005), and 
may directly affect conservation efforts. 
Entire seeds passed through the gut of frugivore 
birds often have increased germination "rates, 
although they may also lose viability and reduce 
Departuinento de Biotogfa Vegetal y Ecologt'a. Uni 
verst dad de Sevilla. Apartado 1095. 41080 Sevilla. Spain. 
- Untvers.dad Central de Ecuador. Ciudad Universitaria 
Quito, Ecuador. 
’Secretariat of the Pacific Regional Environment Pro 
gramme. P. O. Box 240. Apia, Samoa. 
Corresponding author; e-mail: jorgccarrion@us.es 
germination (Traveset 1998. Orrock 2005. D’Avila 
el al. 2010). Seed predators may also contribute to 
dispersal if pulp is consumed and seeds are 
discarded in suitable microsites (Shiels 2011). 
However, when seeds are crushed before ingestion, 
their viability is reduced as recently demonstrated 
tor frugivores and seed predators in the Galapagos 
Islands (Buddenhagen and Jewell 2006, Guerrero 
and Tyc 2009, Guerrero and Tye 2011). 
Lantana camara (Verbenaceae) (Supirrosa) is 
one of the most invasive plants in the Tropics, 
now occupying a wide variety of habitats in 
countries worldwide (Parsons and Cuthbertson 
2001). It was introduced to the Galapagos Islands 
us an ornamental species in 1938 (Tye 2001 > and. 
in 1987. covered >2,000 ha (Lawesson andOrti/ 
1990). L. camara produces a great number ol 
fruits (Sharma et al. 2005) that are usually 
dispersed by frugivorous birds (Day et al. 2003' 
However, no specialist frugivores occur in the 
Galapagos Islands and most landbird species cl 
the archipelago were traditionally considered to 
be granivores (seed predators) or insec tivores 
(Guerrero and Tye 2009). However, some birds, 
including Darwin’s finches, may act as dispersers 
for short and long distances of endemic, natn 
and introduced plants (Buddenhagen and Jewel 
2006; Guerrero and Tye 2009, 2011: Heleno et 0 
2011). Guerrero and Tye (2009. 2011). report 
Darwin’s finches and other Galapagos birds 
demonstrate three main types of fruit-seed han¬ 
dling techniques: (I) swallow die entire fmrt lir 
pieces of it, (2) discard the seeds, eating only the 
pulp, and (3) crushing the fruit and seed Our 
objectives were to: (1) analyze the interaction o' 
Galapagos bird species with L. camara fruit'’ 
338 
