Effect of passage through the gut of Greater Rheas on the germination of seeds of plants of cerrado and caatinga grasslands Cristiano Schetini de Azevedo A,D , Mayara Correa da Silva B , Tatiane Pinho Teixeira B , Robert John Young C , Queila Souza Garcia B and Marcos Rodrigues A A Laboratório de Ornitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Avenida Antônio Carlos 6627, Pampulha, Belo Horizonte, Minas Gerais, Cep: 31270-901, Brazil. B Laboratório de Fisiologia Vegetal, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, 6627, Pampulha, Belo Horizonte, Minas Gerais, Cep: 31270-901, Brazil. Email: tpteixeira@gmail.com; queilagarcia@gmail.com; biologamayara@yahoo.com.br C Conservation, Ecology and Animal Behaviour Group, Pontifíca Universidade Católica de Minas Gerais, Avenida Dom José Gaspar 500, Cora¸ cão Eucarístico, Mestrado em Zoologia (prédio 41), Belo Horizonte, Minas Gerais, Cep: 30535-610, Brazil. Email: robyoung@pucminas.br D Corresponding author. Email: cristianoroxette@yahoo.com; ornito@icb.ufmg.br Abstract. Frugivorous seed-dispersers play an important role in the maintenance or regeneration of plant populations and communities. Greater Rheas are potentially one of the most import dispersers of seeds in South American grassland biomes owing to their capacity to swallow large seeds and their habitat of walking long distances each day. We studied the potential role of Greater Rheas in the dispersion of seeds of plants of the cerrado and caatinga grassland biomes through germination experiments. We evaluated the rate of seed germination and the mean time of germination of passage through the gut (seeds that passed through the digestive system of Rheas) compared with a control (seeds extracted directly from fruits). Nine species of plant from cerrado grasslands and three plant species from caatinga grasslands were tested. All three caatinga plant species germinated at a lower rate and took longer to germinate after passage through the gut, whereas two of nine cerrado plant species germinated at a higher rate and in less time after passage through the gut. Greater Rheas are probably good dispersers of some of the plant species we examined and may therefore be important in maintenance and regeneration of habitat. Future experiments will investigate the factors causing the variation in germination of seeds seen in this experiment. Additional keywords: Passiflora, ratites, Solanum, Spondias, Talisia. Received 29 July 2012, accepted 20 December 2012, published online 8 April 2013 Introduction Birds and mammals are the main dispersers of seeds in the Neotropics (Wilson and Traveset 2000). The cerrado and caatinga biomes of South America are two of the largest biomes in Brazil, comprising 34% of Brazilian territory (cerrado, 24%; caatinga, 10%; IBGE 2004). The cerrado biome is characterised by a seasonal climate (wet, October–March; dry, April–September) with average temperatures ranging from 22 to 27  C and an average annual rainfall of 1500 mm (Klink and Machado 2005). The biome is rich in biodiversity, with more than 7000 species of plants and 1000 species of birds and mammals (Aguiar et al. 2004). Vegetation is a mosaic of grasslands, savannas, woodlands and forests (Coutinho 1976; for more details see Oliveira and Marquis 2002). The caatinga biome is dry woodland, with deciduous plants and thorny shrubs of north-eastern Brazil (Albuquerque 1999). Temperatures of the biome range from 26 to 28  C and rainfall is irregular, mostly concentrated in 3 consecutive months (on average annually 500–750 mm) (Nimer 1972). The biodiversity was first considered low, but recent studies have shown that this is not the case; more than 932 species of vascular plants and 650 species of birds and mammals have been described for the biome (Leal et al. 2005; for more details see Leal et al. 2003). Birds (Guerta et al. 2011) and mammals (Camargo et al. 2011) have also been found to be the main seed dispersers in the cerrado grasslands. There have been few studies of seed dispersal by birds in the caatinga (de A. Moura and McConkey 2007; Leal et al. 2007; Ribeiro et al. 2008) but ants (Leal et al. 2007), mammals (de A. Moura and McConkey 2007) and reptiles (Ribeiro et al. 2008) have been reported to play an important role in seed dispersal. Greater Rheas (Rheidae : Rhea americana) are omnivorous flightless birds that inhabit the grasslands of the cerrado and caatinga biomes (Sick 1997). Greater Rheas are the largest species of bird of South America, standing 1.34–1.70 m tall and weighing CSIRO PUBLISHING Emu, 2013, 113, 177–182 Short Communication http://dx.doi.org/10.1071/MU12070 Journal compilation Ó BirdLife Australia 2013 www.publish.csiro.au/journals/emu