Bird Nests. Materials: Demonstration nests. Paper. Markers. Collection baskets. 1 plastic cup for each student. White modeling clay for making eggs

Transcription

1 Blue Heron Nature Preserve Bird Nests Materials: Demonstration nests Paper Markers Collection baskets 1 plastic cup for each student White modeling clay for making eggs SUMMARY This activity is designed to introduce students to the fascinating world of birds and their nests. Students will learn to think like a bird does about what materials it will gather to make the home for its eggs and nestlings, how it will construct the nest, and where it might build its nest in nature. INTRODUCTION (15 MINS) 1. Ask students to think about the purpose of a nest and what affects its construction. 2. Ask students to describe a bird nest. Show examples of nests. 3. (Optional) Students think about the bird who will live in their nest (can be made fictional) and draw bird. 4. (Optional) Students can draw a design for their nest and/or to write down the kinds of materials they want to collect. Collect nest material on Preserve (45 mins) Gather nest materials from different parts of the Preserve with collection baskets. Look on the ground for dead materials. Children may venture off of the path in search of nest material. Build the nests (15 mins) Return to the building to begin construction on the nests. Use plastic cups to create hold nest or create a free-form nest on matte board or paper. Clay can be used to make birds eggs (only a small amount is necessary for each nest), or children can collect smooth pebbles/rocks to serve as eggs.

2 Extension Activities If there is more time available, the children can spend more time outside looking for birds' nests or looking inside some of the bird boxes that Blue Heron has provided for birds on the property. Students could also create some of the courts or bowers that some male birds create to attract a mate (for more information on courts and bowers, see background information).

3 BACKGROUND INFORMATION Purpose of Birds' Nests The primary reason that birds construct nests is to hold their eggs while they are incubating, and sometimes to house chicks while they develop. If a nest is to be a successful home for the eggs, it must take into account the following considerations: How will the nest physically hold the eggs and what size should it be? Do the chicks require protection and care, or can they survive on their own once they have hatched? How will the nest protect the eggs from the weather, including temperature extremes and rain? How will the nest protect the eggs from predators, either through camouflage or consideration in its construction? How will the bird construct its nest to consider the waste produced by the chicks or parasites that might live on the chicks? Constructing a Nest In addition to thinking about what kind of nest would be best for its eggs, a bird must also consider with what it has to work in order to construct a nest. A bird must consider the following about its surroundings: In what type of habitat does the bird live and find its food? Does it live in a forest, a grassland, a desert, a wetland, or an island? Based on the bird's habitat, where is the best place to construct the nest? Should the bird build the nest on the ground, in the water, or in a tree? Once the bird has picked a place to build its nest, what materials does it have available to create a nest? Does their habitat have grasses, twigs, moss, spider webs or mud? Should the bird build its nest with other birds in a colony, or keep it separate from others in its species? All of these factors will determine how the bird's nest is constructed. Remember, the bird does not have hands to build things as humans do. They rely primarily on their beak, feet, and sometimes their chest to help them construct their nests. Types of Bird Nests As a group, birds use an incredible variety of methods to create a great number of nest types. Below are descriptions of the major types of nests. For an excellent source of more detailed information, please refer to Avian Architecture: How Birds Design, Engineer and Build by Peter Goodfellow.

4 Scrape Nests Game birds (e.g. grouse), ducks, waders and ostriches Scrape nests are the simplest type of nest constructed within the bird world. Scrape nests are common in areas where habitats are open and materials for construction are limited, such as in the desert. This type of nest is simple, frequently with little protection from predators and no lining for eggs. Birds that make scrape nests primarily rely on camouflage to hide their nests, eggs, chicks and sometimes themselves from predators. Yet despite its simplicity, scrape nests must be constructed precisely in order to provide the appropriate temperature conditions for the eggs. A female constructs a scrape nest by lowering herself to the ground and turning in circles to form a shallow depression, sometimes adding additional materials to the nest from nearby (such as pebbles). Cavity Nests Kingfishers, woodpeckers, burrowing owl, ducks, hornbills Cavity nesters create or utilize holes in trees or in the ground as the site of their nests. The advantages of nesting in these well-protected holes or tunnels are great: they provide excellent shelter from the elements and from predation. But due to limitations in possible locations, birds can sometimes experience intense competition for nesting sites. This is particularly true among secondary cavity nesters, who, unlike primary cavity nesters who construct their own nest holes, depend on natural or existing holes for their nests. Constructing a new cavity nest can be a major undertaking, and primary cavity nesters are equipped with beaks or bills that have evolved to drill into the wood of dead trees (e.g. woodpeckers) or the mud of river banks (e.g. kingfishers). To control temperature, birds may strategically select an opening for their nest or line the nest for warmth. Platform Nests Predatory birds, herons, egrets, storks, spoonbills Some of the most conspicuous and striking nests in the avian world are platform nests. Platform nests are commonly constructed at great heights in trees or on buildings in order to provide its builders with a panoramic view of their territory. Other types are constructed lower to the ground in bushes or reed beds. Platform nests are characterized by their "piled up" construction and appearance, often with a shallow or non-existent cup for the eggs. Platform nests often require the participation of both partners in the pair due to the size and energy demands in constructing one.

5 Aquatic Nests Jacanas, marsh terns, grebes, rails Aquatic nests are limited to members of only four families of birds, restricted to birds that almost exclusively use aquatic habitats. Consequently, aquatic nests are constructed using aquatic plant materials and anchored to living plants, which the birds pile into mounds or form into floating islands in deeper water. Nests constructed in water are naturally protected from land-based predators, and they can be well hidden among aquatic vegetation. But the hazards of building a nest on the water include destruction from weather, isolation during drought conditions and accidental loss of eggs that get knocked out of the nest by the incubating bird. Given these threats to eggs and young birds, the nestlings are highly developed when the hatch. Cupped Nests Widespread among bird groups The most commonly recognized bird nest type are cupped nests, in part because of their widespread use in the avian world. But cupped nests are as varied as they are common, constructed from myriad materials including grass, roots, stems, twigs, lichen, flowers and mud. The size and shape of the nest is often highly correlated with the size and shape of the builder (usually the female). The advantages of this nest strategy are readily apparent: the nest is strong and its cup-shape offers protection and insulated lining for eggs and young, and it keeps growing chicks together. Some species extend the cup structure to include a domed roof, which is thought to provide additional security from predators and the elements. With the extra protection afforded by the cupped nest strategy, chicks are born helpless and require greater parental care. However, even cupped nests are not completely resistant to predation, parasitism and squatters. Mud Nests Swallows, martins, magpie-larks A small percentage of birds construct their nests predominantly from mud, combined with some plant materials and the saliva of the bird to increase adhesion strength. For bird species capable of making them, mud nests offer a number of advantages over the more familiar cup nest. Mud nests are strong and durable, capable of being used for more than one year. Because of the plasticity of mud structures, birds can easily construct mud nests to their desired size and shape specifications. While cupped nests can also be enclosed and well-protected shelters for eggs, cup nests cannot be constructed on vertical surfaces with no support from beneath, such as cliffs and cave walls, as mud nests can. However, mud nest builders face similar challenges to potters working with clay: if the mud in their nests dries too quickly or traps air inside, it can cause structural weaknesses. To address this, mud nest builders shake their heads against the nest when applying new mud to distribute moisture evenly throughout.

6 Hanging and Woven Nests African weaverbirds, oropendolas, caciques and orioles The ultimate example of avian architecture can be found among the hanging and woven nests of the bird world. Birds that create hanging and woven nests use an intricate and tedious series of weaving, stitching and knotting to construct their nests from grass materials or banana leaves. Woven nests come in a variety of shapes and configurations, frequently consisting of a long tubular entrance and a cupped inner compartment that houses the eggs and nestlings. Often these nests are built at the extreme edge of a tree or bush where they are out of the reach of most arboreal predators. Mound Nests Megapodes, flamingos Mound nests consist of somewhat simplistic piles and pits that their bird builders create on the ground. True mound builders (the megapodes) carefully construct mounds that self-incubate their eggs, which they bury inside. With no parental incubation or protection required, the adult birds leave the nest and the baby birds hatch more developed than other types of birds when they are born. Other birds, like flamingos, use mud or rock mounds to elevate their eggs off of the ground and provide more traditional parental care to their eggs and chicks. Colonial Nests Wide Variety Colonial nesting is ubiquitous across the bird world, and consequently construction types for colonial nests include a variety of nest types that have already been discussed. Equally variable is the amount of interaction that birds have with other members of their colony. In some colonies, birds breed and nest in close proximity to other members of their species, but do not offer one another any direct help. This group includes birds such as penguins, gulls and martins. Other colony nesters are more cooperative; social weavers construct one huge nest in which each pair of birds occupies a separate compartment. The most communal bird group has a highly organized social structure, in which only a few females lay eggs and all other members of the group feed the nestlings. While nesting in colonies offers birds more protection, it also increases their visibility to predators. Neighbors within a colony can become aggressive if competition for nest sites or food is high.

7 Courts and Bowers While courts and bowers do not technically serve the same purpose as nests, they are fascinating expressions of birds' skills and creativity as builders. Male birds of a small number of species create specialized structural pieces known as bowers or courts and lawns. These structures do not hold eggs, but ; in some cases, the bower itself is the attractor, while in others it serves a supporting role in the male bird's courting performance. These "statement pieces" are carefully decorated with a variety of materials, including attractive leaves and flowers. Interestingly, skillful and effective bower construction requires practice: it may take a male bird seven years of bower building before he successfully attracts a mate.

8 Basic Bird nest field guide