Do larger frugivores move seeds further? Body size, seed dispersal distance, and a case study of a large, sedentary pigeon

Abstract

Aim World-wide declines in large-bodied frugivores may change seed deposition patterns dramatically if body mass influences seed dispersal-related traits, such as dispersal distance. We quantified movement patterns and seed dispersal distances by Hemiphaga novaeseelandiae (kereru), the fifth-largest surviving pigeon world-wide. We then reviewed how body mass affects seed dispersal distance among fruit-eating birds globally.Location Taranaki and Canterbury, New Zealand. MethodsWe radio-tracked 24 kereru, following each bird continuously for up to 8.5 h, for a total of 43 tracking-days during the peak fruiting season (February-April). We estimated seed dispersal distances for three fleshy-fruited species using a mechanistic model based on kereru movements and seed retention times. We analysed global data for volant avian frugivores to determine the effect of body mass on time spent in fruiting trees, seed retention time, and dispersal distance.Results Kereru were highly sedentary, with an average of 32 ± 39 (mean ± SD) minutes and maximum of 315 minutes between flights. Kereru flew a mean of 77 ± 159 m and maximum of 1457 m in a single flight. They dispersed 66-87% of ingested seeds away from the parent plant. Mean seed dispersal distances for Beilschmiedia tawa, Vitex lucens and Pseudopanax arboreus were 95, 98 and 61 m, respectively, with all species dispersed up to 1469 m. For all three species, 79-88% of seeds were dispersed < 100 m and < 1% were dispersed > 1 km from the parent plant. Globally, both the mean time spent in fruiting trees and seed retention time increased with increasing frugivore body mass. However, retention time increased faster, and therefore the dispersal distance and percentage of seeds moved away from the parent increased with body mass.Main conclusions Despite sedentary behaviour, kereru disperse many seeds away from the parent plant due to their even longer gut passage time, a function of their large size. Large-bodied frugivores are disproportionately important as dispersers not only because they can swallow larger fruits, but also because they are more likely to deposit seeds away from the parent plant and at greater distances.

Extinction‐driven changes in frugivore communities on oceanic islands

“…Large-bodied frugivores are disproportionately important as dispersers because they can swallow or handle large fruits and deposit seeds far away from the parent plant (Blake et al 2012, Wotton andKelly 2012). For two large-seeded New Zealand tree species, field experiments suggest that dispersal failure reduces plant regeneration through effects on seed predation, germination and seedling survival (Wotton and Kelly 2011).…”

“…for the colonization of oceanic islands Jones 1994, Nathan 2006). Moreover, large-bodied frugivorous birds such as pigeons or flightless birds such as the dodo (Meehan et al 2002, Hansen and Galetti 2009, Wotton and Kelly 2012 as well as reptiles such as lizards and tortoises are especially relevant for seed dispersal on islands (Olesen and Valido 2003, Blake et al 2012, Hansen and Traveset 2012. Hence, on islands all three vertebrate groups (birds, mammals and reptiles) are important seed dispersers, and the particular traits of frugivores (e.g.…”

Functional Equivalence in Seed Dispersal Effectiveness of Podocarpus parlatorei in Andean Fruit-Eating Bird Assemblages

“…Large body mass species usually remove larger numbers of fruits and move seeds over longer distances than small species (Nathan et al, 2008;Wotton and Kelly, 2012;Morales et al, 2013). Although fruit-eating assemblages recorded in this study were entirely composed of small-sized birds (<100 g body mass), at least three medium-to-large bird species also dispersed P. parlatorei seeds in the undisturbed forest sites.…”

The role of Lithodoras dorsalis (Siluriformes: Doradidae) as seed disperser in Eastern Amazon

“…Besides increasing germination performance, disperser's body zise, regardless of the species, can also influence the seed dispersal effectiveness (Schupp et al, 2010;Wotton, Kelly, 2012;Correa et al, 2015b;Li et al, 2016). Individuals of different sizes can generally differ in their diets due to morphological limitations during periods of development (Abelha et al, 2001;Dala Corte et al, 2016).…”