Birds as seed dispersers in deserts: suggestions from the ground-jays

The study of seed dispersal, biotic seed dispersal, and even less, the role of birds in it, have been almost neglected in deserts. Virtually absent from the literature on seed dispersal are the ground-jays, genus Podoces, four species of the crow family that inhabit arid environments, even true deserts, from Iran to Mongolia. Although they are omnivorous, they seem to mainly depend on the seeds of desert plants during the cold season. There are suggestions in sparse literature that they may contribute to seed dispersal similarly to several corvid species of other climates, by caching seeds in useful microsites to save them for later consumption and thus actually favoring the germination of the seeds they fail to recover. Future research might benefit from comparison with the vast literature on their better-known seed-caching relatives. This paper is aimed at providing basic information on each ground-jay species and some suggestions for investigating their likely symbiosis with desert plants, with possible applications to the maintenance and restoration of vegetation in a very extended arid zone.

Seed caching by rodents favours seedling establishment of two palm species in a lowland Atlantic forest remnant

Scatter-hoarding by rodents is expected to benefit palm recruitment by allowing cached seeds to escape predation and to colonize new areas, but evidence that seedlings emerge from cached seeds is scarce. We aimed to assess to what extent seedling establishment of two palm species (Astrocaryum aculeatissimum and Attalea humilis) is favoured by seed caching by rodents in a large Atlantic Forest remnant. We mapped the location of conspecific seedlings within circular plots of 15-m radius around five adult individuals of each palm species, checking if seedlings established from dispersed (>2 m from parent palms) or non-dispersed seeds (0–2 m from parent palms), and from buried or unburied seeds. We found a total of 42 A. aculeatissimum seedlings and 16 A. humilis seedlings. Nearly all (98%) seedlings established from seeds dispersed away from parents (mainly located 10–15 m from parents), and 83% and 75% of seedlings of A. aculeatissimum and A. humilis, respectively, established from seeds buried in the soil. Results show that both palm species depend almost entirely on caching of seeds by rodents to establish seedlings. Our study suggests that checking for endocarps associated with established seedlings can accurately estimate the process behind seedling establishment, improving our understanding about the net outcome of seed caching for large-seeded palms.