Internal seed dispersal by parrots: an overview of a neglected mutualism

BLANCO, GUILLERMO; BRAVO, CAROLINA; PACIFICO, ERICA C.; CHAMORRO, DANIEL; SPEZIALE, KARINA L.; LAMBERTUCCI, SERGIO A.; HIRALDO, FERNANDO; TELLA, JOSÉ L.

PeerJ

PeerJ

Año: 2016 vol. 4

Despite thefact that parrtos (Psitaciformes) are generalist apex frugivores, they havelargely been considered plant antagonists andthus neglected as seed dispersersof their food plants. Internaldispersal was investigated by searching for seedsin faeces opportunisticcally collected at communal roosts, foraging sites andnests of eleven parrot species in different habitat and biomes in theNeotropics. Multiple intact seeds of sevenplant species of five families werefound in a variable proportion of faeces from four parrot species. The meannumber of seeds of each plant species per dropping ranged between one and aboutsixty, with a maximum of almost five hundred seeds from the cacti Pilosocereuspachycladus in a single dropping of Lear´s Macaw (Anodorhynchus leari). Allseeds retrieved were small (<3mm) and corresponded to herbs and relativelylarge, multiple-seeded fleshy berries and infrutescences fromshrubs, trees andcolumnar cacti, often also dispersed by stomatochory. An overview of the potentialconstraints driving seed dispersal suggests that, despite the obvious sizedifference between seeds dispersed by endozoochory and stomatochory, there isnoclear difference in fruit size depending onthe dispersal mode. REgardless ofthe enhanced or limited germination capability after gut trnsit, a relativelylarge proportion of cacti seeds frequently found in faeces of two parrotspecies were viable according to the tetrazolium test and germinationexperiments. The conservative results of our exploratory sampling and aliterature review clearly indicate that the importance of parrots asendozoochorous dispersers has been largely under-appreciated due to the lack ofresearch systematically searching for seeds in their faeces. We ecourage theevaluation of seed dispersal and other mutualistic interactionsmediated byparrots before their generalized population declines contribute to the collapseof key ecosystem processes.