Über die Autorin bzw. den Autor

Peter Goodfellow is a retired English teacher and lifelong birdwatcher. His books include Birds as Builders and A Naturalist's Guide to the Birds of Britain and Northern Europe.

Auszug. © Genehmigter Nachdruck. Alle Rechte vorbehalten.

AVIAN ARCHITECTURE

Princeton University Press

Contents

Foreword......................................................6Introduction..................................................8Chapter 1 Scrape Nests........................................10Chapter 2 Holes & Tunnels.....................................22Chapter 3 Platform Nests......................................34Chapter 4 Aquatic Nests.......................................46Chapter 5 Cup-Shaped Nests....................................56Chapter 6 Domed Nests.........................................70Chapter 7 Mud Nests...........................................84Chapter 8 Hanging, Woven & Stitched Nests.....................94Chapter 9 Mound Nests.........................................108Chapter 10 Colonies & Group Nests.............................122Chapter 11 Courts & Bowers....................................132Chapter 12 Edible Nests & Food Stores.........................144Resources.....................................................154Glossary......................................................156Index.........................................................157Acknowledgments...............................................160

Chapter One

The builders of scrape nests are the minimalists of the avian architecture fraternity. Faced with the challenge of an open habitat with limited materials, they literally scratch out an existence by gouging a shallow nest out of the ground. The scrape nest is exactly as it sounds: a scrape or depression in the earth, sometimes with material added to create a lining. Primarily an area for eggs and their incubation, the ground-level scrape offers quite limited defenses. Camouflage is therefore essential, and the scrape nest, eggs, and young are adapted to blend with the ground.

To start constructing a scrape, usually the hen will lower herself onto her breast at the chosen site and rotate and shuffle with her feet to form a shallow depression in the sand, shingle, or vegetation. Many birds line their scrapes, the amount of lining varying with the species and individual, and two building methods are used. First, as a pair moves away from or around the scrape site they pick up nest material—bits of vegetation, small pebbles, shell fragments—and use a technique called "sideways throwing" to toss the objects to the side of or beneath them. Second, the sitting bird pulls at the material and tucks it alongside or beneath her—this is "sideways building."

Some of the simplest scrapes are those of shore-nesting plovers. Wildfowl make more elaborate scrapes and add a layer of down. The Common Eider (Somateria mollissima) builds in the shelter of rock or vegetation and plucks feathers and down from her breast to establish a thick lining.

Despite its simplicity, the scrape nest demonstrates a degree of precision to effectively shelter the eggs and incubating bird, especially in cold, damp habitats. The scientist Jane Reid and her colleagues found that the scrape of the Arctic-breeding Pectoral Sandpiper (Calidris melanotos) was made to an optimal cup depth to result in the minimum heat loss for the eggs; too deep and the cold ground affected incubation, too shallow and wind chill was a problem.

Vulnerable to predators, the eggs in scrape nests demonstrate excellent camouflage. The eggs of sandy-shore species such as plovers generally have a light base color, finely speckled with gray or black. Waders that nest on grasslands, tundra, or marshes lay eggs with a darker base color, as befits the nest site. Ducks' eggs are plainly colored and rely on being hidden by undergrowth and down.

Various features aid the chicks' survival. They often leave the nest soon after hatching, and are precocial (able to walk almost immediately), and nidifugous ("nest flyers"—they flee the nest to seek food, guided by the parents). Their camouflaged plumage protects them when a parent's alarm call makes them crouch stock still.

BLUEPRINTS

Scrape Nest Structures

The architectural blueprint for a scrape nest includes the shallow indentation on a ground site; precise depth to achieve optimal egg temperature; simple lining materials; and strong camouflage features. Species with scrape nests include game birds (pheasants, grouse, partridges); ducks; waders (shore-nesting plovers); the Short-eared Owl (Asio flammeus); and, the Ostrich (Struthio camelus).

VARIETIES OF STRUCTURE

Sites include open ground, boggy ground hidden by growing vegetation, and slightly elevated platforms. The Short-eared Owl makes a scrape in heather moors, tall grass, dead reeds, and marram grass on dunes. Scrapes are sometimes lined with materials including plant stems, leaves, grass, shell fragments, and pebbles. Eggs may be camouflaged or buried for protection.

MATERIALS AND FEATURES

Courser Nest

The coursers form a special subfamily of waders that has evolved into a group of eight species. They inhabit semi-desert or other almost bare ground in Africa and India. The most widespread is the Cream-colored Courser (Cursorius cursor), which is found in barren country bordering the north and south of the Sahara in North Africa. All except one species are mostly sandy colored. The courser's scrape nest is little more than a scratching in the sand, and normally two eggs are laid directly onto the ground. This minimalist architecture in fact provides the nest's primary defense, because the lack of structure together with the superb camouflage of eggs and chicks can make it virtually invisible. If it is disturbed, the courser has long, strong legs that enable it to run well (cursor means "a runner" in Latin). It runs in a hunched manner, then stops suddenly and stands tall, with neck stretched up for a view of the intruder.

Invisibility

The courser nest uses camouflage as its primary defense. The nest structure is inconspicuous, and the eggs are camouflaged by a pale buff color finely spotted with brown. When the adult lands, as British Museum scientist David Bannerman wrote, "the bird will almost fade from view," so closely does it match the ground color. The chicks are even better camouflaged; their pale sandy-rufous down is lightly speckled with white and gray and they lack the adults' striking head pattern. The combined effect is a cloak of invisibility.

Temperature control

This Temminck's Courser (Cursorius temminckii) is photographed in the Gambia, West Africa, where temperatures remain high all year. Due to the exposed nature of the nest, scrape-nesting birds in desert habitats need to prevent their eggs overheating. Panting, ruffling their feathers, and standing over their eggs or chicks to provide the nest with an improvised sunshade, instead of incubating or brooding, help to solve the problem. Double-banded Coursers (Rhinoptilus africanus) of East and South Africa share standing over the egg, and later the chick, to protect them from the sun's direct heat as well as radiated heat from the sand.

Additional camouflage

Many courser scrapes are constructed with no added material beyond the ground that they are built on. Some, however, like the main nest illustration here, have been found to feature an ingenious additional piece of architectural design. A ring of animal dung is constructed around the eggs to...