Parrots as key multilinkers in ecosystem structure and functioning

Abstract

Mutually enhancing organisms can become reciprocal determinants of their distribution, abundance, and demography and thus influence ecosystem structure and dynamics. In addition to the prevailing view of parrots (Psittaciformes) as plant antagonists, we assessed whether they can act as plant mutualists in the dry tropical forest of the Bolivian inter‐Andean valleys, an ecosystem particularly poor in vertebrate frugivores other than parrots (nine species). We hypothesised that if interactions between parrots and their food plants evolved as primarily or facultatively mutualistic, selection should have acted to maximize the strength of their interactions by increasing the amount and variety of resources and services involved in particular pairwise and community–wide interaction contexts. Food plants showed different growth habits across a wide phylogenetic spectrum, implying that parrots behave as super‐generalists exploiting resources differing in phenology, type, biomass, and rewards from a high diversity of plants (113 species from 38 families). Through their feeding activities, parrots provided multiple services acting as genetic linkers, seed facilitators for secondary dispersers, and plant protectors, and therefore can be considered key mutualists with a pervasive impact on plant assemblages. The number of complementary and redundant mutualistic functions provided by parrots to each plant species was positively related to the number of different kinds of food extracted from them. These mutually enhancing interactions were reflected in species‐level properties (e.g., biomass or dominance) of both partners, as a likely consequence of the temporal convergence of eco‐(co)evolutionary dynamics shaping the ongoing structure and organization of the ecosystem. A full assessment of the, thus far largely overlooked, parrot–plant mutualisms and other ecological linkages could change the current perception of the role of parrots in the structure, organization, and functioning of ecosystems.

Endangered plant-parrot mutualisms: seed tolerance to predation makes parrots pervasive dispersers of the Parana pine

“…3). Importantly, as recorded for the congeneric monkey puzzle tree Araucaria araucana 10 and other plant species89173940, parrots can act as primary dispersers by moving most seeds long distances (hundreds of meters), which can have a pervasive influence in the genetic structure of populations. Genetic mapping of all living trees showed the realized dispersal of seeds within a 7.2 ha plot of Parana pine forest, dispersal reaching 318 m with 50% of seeds being dispersed up to 133 m41.…”

Diet of Neotropical parrots is independent of phylogeny but correlates with body size and geographical range

“…Approximately 30% of parrot species are threatened by habitat loss, fragmentation and the pet trade (Olah et al 2016, Berkunsky et al 2017, Collar 2017, IUCN 2017). In ecological terms, parrots play a key role in the functioning and maintenance of biodiversity by establishing antagonistic and mutualistic interactions with numerous plant species (Dirzo & Miranda 1991, Coates Estrada et al 1993, Blanco et al 2015, Baños Villalba et al 2017, Montesinos Navarro et al 2017. In a worldwide review of the resource requirements of parrots, Renton et al (2015) found that parrots are trophic generalists with a high plasticity in diet, consuming a wide variety of food items such as seeds, fruits, flowers and nectar from a high diversity of plant species (Lee et al 2014, Blanco et al 2015, Renton et al 2015.…”

“…In ecological terms, parrots play a key role in the functioning and maintenance of biodiversity by establishing antagonistic and mutualistic interactions with numerous plant species (Dirzo & Miranda 1991, Coates Estrada et al 1993, Blanco et al 2015, Baños Villalba et al 2017, Montesinos Navarro et al 2017. In a worldwide review of the resource requirements of parrots, Renton et al (2015) found that parrots are trophic generalists with a high plasticity in diet, consuming a wide variety of food items such as seeds, fruits, flowers and nectar from a high diversity of plant species (Lee et al 2014, Blanco et al 2015, Renton et al 2015. Furthermore, they employ a variety of foraging strategies, adjusting their behaviour to seasonal food availability and even adapting to alternative and novel food sources in modified environments (Matuzak et al 2008).…”

From the cage to the wild: Introductions of Psittaciformes to Puerto Rico

“…Some parrots are known to be both seed predators and dispersers (Norconk, Grafton & Conklin Brittain, 1998;Francisco et al, 2002;Blanco et al, 2015;2016;Blanco et al, 2017), and both seed predation and seed dispersal have important implications for ecosystems dynamics worldwide, and help regulate plant recruitment, competition, and population structure (Howe & Smallwood, 1982;Hamrick et al, 1993;Nathan & Muller-Landau, 2000). Unlike other birds, parrots have specialized bills that allows them to access resources, such as hard seeds, that are often not available to other animals, and they often destroy seeds in the wild.…”