Abstract
In the frugivory networks of many arid and semi‐arid Mesoamerican ecosystems, columnar cacti act as keystone species that produce fruits with a high content of water and nutrients attractive to numerous vertebrates. The aim of this investigation was to assess the fruit removal patterns of two guilds of frugivores on the fruits of the woolly torch Pilosocereus leucocephalus. We assessed fruit pulp removal in two ways: by estimating the consumption of seeds given the amount of pulp removed per visit and by estimating the percentage of pulp removal over time. We put exclosures on unripe, intact fruits to keep frugivores from removing material. Once ripe, we removed the exclosures and tracked animal visitation of 69 fruits using camera traps. We obtained a total of 2,162 hr of footage (14:47 hours of them with effective pulp removal). The highest number of visitors is that of diurnal species (n = 12, all birds) versus only four nocturnal (three bats, one rodent). The most effective species in pulp removal are birds. Bats play a modest role in frugivory of this cactus. The significance of this work is twofold: (a) birds and bats consume the fruit pulp of this cactus and likely disperse its seeds, and (b) although bats rank high in pulp removal effectiveness, birds as a guild far outweigh their importance in this system, as they are not only more frequent but also remove more pulp and seeds. Both groups are known to be important in cacti seed dispersal, and our findings are essential in understanding the population dynamics of the woolly torch and in elucidating its seed dispersal ecology.
Highlights
We hypothesized that a quantitative assessment of pulp removal by different animal visitors would help us move beyond basic de‐ scriptions and allow us to uncover some of the ecological processes that underlie the frugivory patterns of this cactus, since many aspects of the ecology of fruit‐bearing plants depend largely on which animal species are charged with dispersing its seeds
This paper provides new information on P. leucocephalus visita‐ tion by birds and mammals
We studied the patterns of frugivory of P. leucocephalus in a natu‐ ral population located at the Rancho San Ignacio, near the town of
Summary
This relationship between plants and animals and its ecological out‐ comes are a result of the interplay among environmental conditions, the reproductive strategy of plants, and the role that animals play in seed dispersal (Gomes, Quirino, & Araujo, 2014; Schupp, Jordano, & Gómez, 2010). The function of columnar cacti in frugivory networks in arid and semi‐arid regions is of paramount importance to our understanding of those ecosystems (Bravo‐Hollis, 1978). In these nutrient‐limited habitats, cacti provide a variety of fruits rich in water and sugars to vertebrates and invertebrates that consume their mucilaginous pulp and presumably help in the dispersal of seeds (Schupp, 1993). We hypothesized that a quantitative assessment of pulp removal by different animal visitors would help us move beyond basic de‐ scriptions and allow us to uncover some of the ecological processes (like the ones listed above) that underlie the frugivory patterns of this cactus, since many aspects of the ecology of fruit‐bearing plants depend largely on which animal species are charged with dispersing its seeds. We assess the role of each guild of visitors in seed dispersal and seed predation given what we know about cacti and their dispersal agents
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