Bird Fact Friday: Gulpers & Mashers

Adapted from page 163 of The New Neotropical Companion:

Birds are selective about the size of the fruits they eat and how they consume them. Species such as toucans, aracaris, and toucanets pluck fruit, juggle it in the bill, and then often reject it by dropping it. Large fruits are particularly at risk of rejection and may be found scarred by bill marks. Nathaniel Wheelwright hypothesized that plants are under strong selection pressure to produce small to medium-size fruits, as larger ones are rejected by most bird species except those with the widest gapes. Thus large fruits will tend to be selected by large birds such as curassows and guans. Large fruits permit more energy to be stored in the seeds, an advantage once dispersal and germination have occurred.

This Grayish Saltator (Saltator coerulescens) is an obvious example of a masher. Photo by John Kricher.

Studies by various researchers in Costa Rica indicated two basic methods by which birds devour fruit. Anyone can observe these methods in the field. Some birds (mashers) mash up the fruit, dropping the seeds as they do, while others (gulpers) gulp the fruit whole, subsequently either regurgitating or defecating seeds. Mashers are mostly finches and tanagers, and gulpers are toucans, trogons, and manakins. Mashers appear more sensitive to taste than gulpers, showing a distinct preference for fruits rich in sugars. Gulpers swallow fruit whole and appear taste insensitive.

New Neotropical Companion CoverThe New Neotropical Companion
John Kricher
Chapter One

The New Neotropical Companion is the completely revised and expanded edition of a book that has helped thousands of people to understand the complex ecology and natural history of the most species-rich area on Earth, the American tropics. Featuring stunning color photos throughout, it is a sweeping and cutting-edge account of tropical ecology that includes not only tropical rain forests but also other ecosystems such as cloud forests, rivers, savannas, and mountains. This is the only guide to the American tropics that is all-inclusive, encompassing the entire region’s ecology and the amazing relationships among species rather than focusing just on species identification.

The New Neotropical Companion is a book unlike any other. Here, you will learn how to recognize distinctive ecological patterns of rain forests and other habitats and to interpret how these remarkable ecosystems function—everything is explained in clear and engaging prose free of jargon. You will also be introduced to the region’s astonishing plant and animal life.