Beaks, Bones, and Bird Songs: How the Struggle for Survival Has Shaped Birds and Their Behavior

by Roger Lederer Narrated by Charles Constant

Overview

When we see a bird flying from branch to branch happily chirping, it is easy to imagine they lead a simple life of freedom, flight, and feathers. What we don't see is the arduous, life-threatening challenges they face at every moment. Beaks, Bones, and Bird Songs guides the listener through the myriad, and often almost miraculous, things that birds do every day to merely stay alive. Like the goldfinch, which manages extreme weather changes by doubling the density of its plumage in winter. Or urban birds, which navigate traffic through a keen understanding of posted speed limits. In engaging and accessible prose, Roger Lederer shares how and why birds use their sensory abilities to see ultraviolet, find food without seeing it, fly thousands of miles without stopping, change their songs in noisy cities, navigate by smell, and much more.

Editorial Reviews

From the Publisher

An exceptional overview of the life, adaptations, and impressive skill sets of wild birds. . . . Highly recommended for all interested in natural history and the impact of humans on the natural world.” ---Library Journal

From the Publisher - AUDIO COMMENTARY

An exceptional overview of the life, adaptations, and impressive skill sets of wild birds. . . . Highly recommended for all interested in natural history and the impact of humans on the natural world. —Library Journal

Library Journal

05/15/2016
This thoughtful, well-researched title comprises seven beefy chapters on migration and navigation, flying skills, foraging behavior, survival strategies (including adaptations to widely varying weather and climate conditions), sensory abilities, and community life, and the effects of human influences. Lederer's (emeritus, biological sciences, California State Univ.; Amazing Birds: A Treasury of Facts and Trivia About the Avian World) review of world literature is impressive, but his compelling, wide-ranging text would be more valuable if cross-referenced to relevant citations in the extensive bibliography. Ninety-four solid black-and-white illustrations showcase many of the birds, habitats, and phenomena so thoroughly described in his narrative, such as the bar-tailed godwit, many of which fly nonstop for seven days from Alaska to New Zealand (6,600 miles), and bar-headed geese, which migrate above the Himalayas. Lederer does a superlative job of incorporating contemporary issues: climate change; urbanization; noise, light, and other pollutions; feral cat predation, glass collision, and other hazards and developing changes. This is an exceptional overview of the life, adaptations, and impressive skill sets of wild birds. VERDICT Highly recommended for all interested in natural history and the impact of humans on the natural world.—Henry T. Armistead, formerly with Free Lib. of Philadelphia

SEPTEMBER 2017 - AudioFile

With an air of admiration and curiosity, Charles Constant narrates this concise, yet surprisingly dense, exploration of birds. Just as the title suggests, the audiobook covers birds from tips to tails and offers significant insight into their behavior and survival strategies, including their response to growing pressures from humans and climate change. Constant's upbeat tone and clear articulation, including slowing down while explaining detailed concepts, prevents listeners from becoming overwhelmed. One minor fault is the lack of distinct pauses between subject headings, which appear regularly throughout each chapter. There's a lot to digest here, so the quick transitions can sometimes seem abrupt. Listeners curious to learn more are encouraged to seek out the book and its many pictures and diagrams, which further enhance the narrative. A.S. © AudioFile 2017, Portland, Maine

Product Details

BN ID:	2940171127251
Publisher:	Tantor Audio
Publication date:	05/30/2017
Edition description:	Unabridged

Read an Excerpt

CHAPTER 1

BIRDS, BEAKS, AND BELLIES

The Whys and Wherefores of Foraging

In birds the mouth consists of what is called the beak, which in them is a substitute for lips and teeth. This beak presents variations in harmony with the functions and protective purposes which it serves.

— ARISTOTLE, On the Parts of Animals

Ever watch birds jockeying for position to snatch the best morsels of seed at a bird feeder? The same phenomenon occurs in the woods, but is not as easily observed as it happens in a much larger venue with a wider variety of birds and food items. Foraging, from the Old French fourrage (to forage, pillage, or plunder), refers to the ways birds find food. This activity, followed by feeding, consumes much of a bird's day. And for good reason: efficient foraging is indispensable for survival. Birds have many other challenges (weather, predators, competitors, migratory journeys) on the way to their fundamental goal of reproduction, but these only add to the burden of finding food.

The feeding behavior of birds has been studied for many years, but in the 1960s ornithologists recognized that birds that maximize their energy intake per unit time spent foraging produce the most offspring. Those birds that ate foodstuffs with less nutritional value or spent too much — or not enough — time seeking food are no longer with us. As a result of this revelation, theimportance of foraging in avian ecology has been reflected in a large percentage of field studies ever since.

Successful foraging is the result of beak (or bill, the terms are interchangeable) shape, which in turn determines much of a bird's lifestyle. The beak, with few exceptions, is the bird's only tool. Birds use their beak not only to forage and feed, but also to preen and oil feathers, defend territories, attack predators, build nests, and aid in courtship displays. So if it is an all-around tool, why aren't all bird bills the same — some perfect all-purpose beak created by evolution? Because natural selection, in its wise ways, reduced competition by making different bills for different foods.

THE EVOLUTION FROM TEETH TO BEAK, THE ULTIMATE TOOL

"Rare as hen's teeth" has come to mean rarity itself. Of all the vertebrate groups (fish, amphibians, reptiles, birds, and mammals) only birds lack teeth as we know them: enamel outcroppings fixed in jaws. About 150 million years ago in the Jurassic Period there lived an almost perfect example of the transition between reptiles and birds — an animal with rooted teeth, a long bony tail, and the abdominal ribs of reptiles, but also feathers. This animal, Archeopteryx (ancient wing), is certainly among the most important fossils ever found and for many years was considered to be the first bird. However, since its discovery in 1861, many other fossils of potential bird ancestors have been uncovered, such as the Chinese fossil Xiaotingia zhengi, discovered in 2011.

Many early birds shared major skeletal characteristics with coelurosaurian (hollow-tailed lizard) dinosaurs: forwardly located pelvic (hip) bones, large bony eye sockets, light, hollow bones, reduced tail vertebrae, elongated arms and hands, and fused clavicles (making the wishbone). They also shared a similar egg structure and some had feathers. As birds evolved, improvements in flying ability required morphological changes, such as the need to weigh less. Teeth became smaller and reduced in number until they finally disappeared. Lighter bills, both hooked and serrated, replaced heavier teeth. Along with bills, birds developed other ways to grasp prey such as tongues and feet with spines or prickles. Whereas toothed mammals chew food to begin digestion, birds simply snatch and quickly swallow food like insects, nectar, fruit, worms, and seeds. To accommodate these changes, the feeding mechanisms of birds became specialized not only in the form of beaks but further down, bellies (crops and gizzards).

A bird's beak is composed of an upper and lower bony jaw covered by a thick layer of keratin, a structural protein, the same substance that forms skin, feathers, scales, fingernails, and turtle shells. This is the rhamphotheca (Greek for beak case or sheath), which grows throughout the year, sometimes changing color seasonally as it does in the European Starling whose wintery black bill becomes yellow in the spring.

Beaks, which evolved for the purpose of food getting, are as varied in shape and size as ice cream flavors, reflecting the diversity of food and its source. Beaks range in size from the African Shoebill's enormous wooden shoe–shaped beak to the miniscule beaks of small finches. Hooked, long, thick, wide, pointed, blunt, up- or downturned, bent, crossed, swollen, or serrated, beaks tear, probe, suck, filter, chip, crack, tweeze, chisel, crush, strain, spear, or seize food items.

Along with differing shapes, styles, and lengths of beaks came different feeding styles. Heavy conical bills handle seeds well, whereas flat triangular bills catch flies easily. Crossbills use their overlapping mandibles for opening pine cones; long-billed shorebirds probe deeply into mudflats locating their quarry without seeing, touching, or smelling it; and skimmers slice through the top of the oceans' waters, snatching food items near the surface. Every bird has its own beak-defined niche; a flycatcher could not survive by feeding on mudflats any more than a sandpiper could live in thick woods.

Bills often serve as sexual signals as well. Male Zebra Finches with bright bills attract females as do puffins with their multicolored beaks. Bird bills also help to regulate body temperature by radiating heat, partially compensating for birds' lack of sweat glands. So sometimes there is a bit of a compromise among the functions of the bill, but eating is the highest priority.

Consider the finches of the Galapagos Islands and their bill shapes. An ancestral finch or two landed on the Galapagos from South or Central America. The birds increased in number and spread to different islands until eventually 14 different species with beak variations came to be. Three species of finches eat seeds off the ground, three more live on cactuses and eat mainly fruit and insects, and one seedeater lives in trees. The rest are arboreal insect eaters, including the tool-using Woodpecker Finch that extracts insect larvae from tree branches with the use of a cactus spine. Evolving a different beak meant exploiting a new food source and sharing the food supply, which benefited everyone.

Every bird has its own technique of seeking out and acquiring sustenance with beak shape defining a range of behaviors and food items. Since we are most familiar with the birds that visit our feeders, let's start with the seedeaters.

SEEDEATERS OR GRANIVORES

Granivory (seed and grain eating) evolved in tandem with birds developing the ability to fly as seeds provide accessible sources of concentrated energy. The lower jaws of granivores are solidly muscularized, enabling the jaw to push the seed upward into the almost immoveable upper jaw. The hard palate of the upper jaw is heavily keratinized and has ridges, bumps, and spine-like projections that serve to husk the seed and direct the digestible part backward.

Seeds are not easy to digest, so after the seeds are swallowed they move to the crop (from the Old English cropp, meaning craw), an expanded part of the esophagus. Most bird species have a crop, but some, like owls and geese, do not. The crop may have evolved as part of the active lifestyle of some birds. Fossil evidence from China indicates that perhaps as far back as 140 million years ago some birds had crops for temporary food storage as did some herbivorous dinosaurs. Rather than eating food slowly and digesting it before moving on, birds with a crop fill it to almost bursting. Digestion then begins as the food slowly makes its way downward. I once found a dead grouse with a fist-sized crop full of juniper needles. Veterinarian Thomas Caceci dissected a Wood Duck and found 10 decent-sized acorns in its crop; that would be like a human throat filled with 10 golf balls.

From the crop the food goes to the small intestine and then the glandular part of the stomach that secretes digestive enzymes, the proventriculus (before the small belly). The second part of the stomach is the ventriculus (small belly) or gizzard, from the Old French gésier, chicken entrails. The gizzard is muscular and, substituting for teeth, mechanically grinds food; it often contains sand grains or small rocks to help in the process. Apparently this organ has fascinated people for years. Spallanzani, an Italian Catholic priest of the 18th century, claimed that he fed turkeys scalpel blades, which the gizzard ground to pieces. Some say that if you hold a live chicken up to your ear you can hear gizzard stones grinding.

From the basic conical shape, seedeater bills vary to match the contours of seeds and their different sizes, shapes, and hardness. Deeper bills have more musculature and exert greater forces, so in general, the deeper the bill, the larger the seed that can be handled. Evening Grosbeaks — so named by French explorers who thought the birds only fed in the evening — have a large bill that can exert enough force to crack open cherry pits. Following robins and other cherry eaters that digest the fruit and regurgitate the seeds, Evening Grosbeaks feast on the pits. The European Hawfinch can crack open olive and plum pits as well and feeds its young by regurgitating partially digested seeds.

Birds typically choose the seeds that are most available and easily handled. At a bird feeder you might find White-crowned Sparrows gingerlymanipulating seeds to husk them, Eurasian Collared Doves gulping larger seeds, and tiny goldfinches picking through the seed pile for smaller, softer seeds. Finches place the seed laterally on the edge of their lower jaw and slide their jaw slightly forward and back to crack it; to husk it, the bird moves the seed to the middle of the palate and moves its jaws laterally until the shell comes off. Watch the dining habits of these birds at your feeder closely and you'll discover lots of different styles, like your relatives at Thanksgiving dinner.

The Red Crossbill is a specialist. Its crossed mandibles and strong jaws enable the bird to pry open the scales of pine cones and extract the small seeds — the bird holds a cone with one foot while extracting a seed. (Interestingly, individuals with the lower mandible crossed to the right hold the cone with their right foot, and left-crossed birds use their left foot.) This adaptation gives crossbills almost exclusive access to this particular seed source, but specialization has its downside. As seed removal takes time, crossbills need seed abundances two to three times greater than other bird species to fill their daily energy requirements as they have less time to forage. The production of seeds in coniferous forests goes down every three to five years, at which time the crossbills are at a disadvantage competing for other kinds of seeds that they can't handle as well.

Acorn Woodpeckers of the western United States and Mexico store acorns in "granary" trees and defend them aggressively. They wedge the acorns into holes in trees or wooden telephone poles so tightly that crows, squirrels, and rats can't raid their supply. To remove an acorn, a woodpecker hammers it with its bill to crack the shell and extract the meat. Clark's Nutcrackers, capable of carrying more than 90 pine seeds at a time in a pouch under their tongue, store many of them in caches, even under the snow. They cache two to three times what they need for the winter and eventually find half or more of their seed caches later. Not only do the birds recall the site of these caches for up to nine months, they also remember the relative number of seeds and the size of the seeds in each cache. Florida Scrub Jays cache food by burying one acorn at a time; if they observe another jay, a potential cache robber, watching them, they will return later to move the acorn. But they will only do this if they themselves were cache robbers in the past. Seems that honest jays trust the other ones and thieves do not.

THE GRAZERS: BIG, SMALL, FLYING, AND FLIGHTLESS

Lots of birds are grazers, and some of them are considered crop pests — blackbirds in North America and Java Sparrows in Indonesia eat rice crops, while parrots damage almond crops in Australia. The Red-billed Quelea of Africa may be one of the worst pests, because, some say, it is the most abundant bird in the world; super-colonies of an estimated 30 million birds have been observed. Flocks are so large that when they land in trees they break large limbs off. A large flock of quelea can eat 50 tons of grain a day and since quelea are kept as pets in Australia, Queensland Biosecurity is concerned about their possible escape and damage to corn, wheat, and cereal crops. One quelea adaptation for survival is the behavior of breaking up into small search parties to hunt for food and then returning to the colony to transmit information about the new food source. Studies indicate, perhaps not surprisingly, that the number of birds and variety of bird species that feed on food crops is much higher in organically grown fields than in non-organic ones. The numbers of insects, as well as weedy plants, are also double or triple in organic crop fields because of the absence of pesticides.

While fishing on my favorite lake, I admired the numerous Canada (not Canadian) Geese overhead, on the water, and in the shoreline grass. Once in serious decline in the early 20th century because of overhunting and habitat destruction, their current North American population may be nearly six million. The birds graze on grass blades, stems, and seeds, grasping the plants with the lamellae (sharp ridges) of their bills. Not possessing a crop, they eat constantly and the not-so-nutritious food, with a large amount of minimally digestible cellulose, moves quickly through the digestive system. This results in a lot of bird pooping, about every 20 minutes, a big reason the birds are considered pests on school grounds, parks, and golf courses. The flightless Kakapo or owl parrot from New Zealand is also a dedicated vegetarian, regurgitating indigestible fiber. It has a small gizzard for a plant eater, probably because its jaw, tongue, and beak structure allow it to grind up plant matter before swallowing. Unusual among land birds, the Kakapo can also store a large amount of body fat, making it the world's heaviest parrot. It is also the world's rarest parrot and perhaps the longest-lived bird at an estimated 90 years.

Grouse and ptarmigan digest about a fifth of the fiber they eat. If they had evolved a fermentation chamber as part of their digestive system, they would be able to process more, but that would add weight to these birds, which are already weak fliers. Adding a fermentation chamber allowed the evolution of flightless birds such as the Ostrich, Emu, and rheas. These large ground dwellers graze on green plants and seeds, digesting much of the cellulose they ingest by fermenting it in their caecum, comparable to our appendix. The efficient gut of the Emu has a muscular gizzard with a strong grinding ability, aided by grit (in addition to small stones in the gizzard, pieces of glass, wood, and metal are occasionally found) and an acid environment. These birds prefer high-energy foods such as fruit and seeds and are able to extract enough energy from plant stems to support up to two-thirds of their daily energy needs. Ostriches, whose gizzards might contain three pounds of material, have been known to eat rings, bottle caps, spark plugs, bicycle valves, and even pieces of baling wire. However, they do not eat tin cans or hide their heads in the sand.

GLEANERS, HAWKERS, AND PROBERS: THREE WAYS TO EAT BUGS

Another major food source is bugs, really arthropods, of every stripe — spiders, flies, millipedes, ants, beetles, and relatives. Birds catch these nutritious creatures in three ways: gleaning, hawking, or probing.

(Continues…)

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Excerpted from "Beaks, Bones, and Bird Songs"
by .
Copyright © 2016 Roger J. Lederer.
Excerpted by permission of Workman Publishing.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

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