Nest watch – 1

Geetha Iyer

Nests bring to mind the birds. They also raise visions of a home for them. Both these are incomplete and wrong presumptions. Nests are not built only by birds but by diverse fauna of the animal kingdom. Secondly they are temporary shelters built by birds and most other animals for the purpose of reproduction. A safe and secure place to lay eggs or give birth and then to rear the offspring till they are ready to lead an independent existence. Several textbooks still describe nests as bird’s homes which is not correct. Although the birds spend a lot of time and energy building them, even the most elaborately and creatively built nests are abandoned once the chicks have grown and departed.

Bird nests are interesting, more so when one can actually see them build it. One of the reasons for the decreasing numbers of sparrows is the non-availability of nesting sites among human dwellings. A small awning or a couple of sloping roofs with planks, a thick bush, a clump of long grasses are more than enough to invite birds to plan their family. Like the diversity exhibited in their size, colour, feathers and form, nests of birds too come in different kinds, forms, and built in different places The intricate weaver bird’s nest, the “leaf-stitched” tailor bird’s nest, the carved out barbet’s nest or the edible swiftlet’s nest made using its saliva, the creativity exhibited by birds in making temporary shelters is awesome! That they can abandon it when the job of raising a new generation is done surely has something for humans to reflect upon. The detachment exhibited by animals is worthy of discussion on ‘values’!

Nest types
Nests are quite diverse and are classified based on the location and/or form. They may be:

Ground nests which could be scrape, hollow depressions or mound nests made on the soil/vegetation; occasionally the bird might add a bit of leaf litter or a few stones here and there. Gulls, terns and other shore birds build this type. Ostriches too build this kind. It requires constant supervision by the adults as such nests are easily prone to predation.

Burrow nests are excavated places made by the bird itself or by other animals; some birds dig their own burrows while some use burrows dug by other animals. Such nests help maintain the microclimate necessary for hatching and growth, and unlike scrape nests that are open to predation, these are effective at protecting eggs and young from predators. Two commonly seen birds that build this kind are the kingfishers and bee-eaters.

Platform nests are the type built on tree tops, on vegetation or on rocky ledges by raptors, owls, pigeons etc.; they are relatively speaking flat nests built on a raised ground. For certain raptors, starlings, and owls, a rocky ledge would be adequate as a nest. Some aquatic birds such as grebe build this kind of nests over debris or rooted vegetation found in water.

Cavity and cupped nests are the main focus of this article.

Cavity nests are typically made in tree trunks – dead wood, trunk of dying trees, or occasionally in living ones too. Woodpeckers and barbets carve out their own nests and are called the primary cavity dwellers, whereas parakeets and mynas happily occupy the cavities excavated by other birds. Such birds are described as secondary cavity dwellers. The magnificent hornbill too is a secondary cavity nester using natural tree hollows or cavities dug by other birds to nest.

The coconut tree – An apartment for birds! The dead coconut tree featured here from my backyard can surely be called a bird apartment. The cavities seen are the work of the large brown barbet, but the builder could only claim one home for itself. The other cavities were usurped by the bird bullies! An aggressive family of parakeets. Soon one of the parakeets abandoned its penthouse space, which was quickly claimed by the mynas. Currently, the five cavities are occupied by (in order of increasing height from below) myna, barbet, and parakeet. A woodpecker which used to hang around here decided that it was too crowded for his liking. It is currently checking out other trees for a possible nesting space, but is yet to find one to its satisfaction.

It is not just lack of living trees but even finding dead trees for nesting is getting difficult for birds. The declining nesting sites are believed to be a reason for decrease in bird population. When a tree dies, humans cut it down without realizing that we are removing a resource very valuable to the birds.

Cupped nests are, as the name says, cup shaped. Such nests may be constructed of various materials and found in a variety of locations. When nest designs are similar, ornithologists identify them by their location and/or size. The cup nest is smoothly hemispherical inside, with a deep depression to house the eggs. Most are made of pliable materials -including grasses – though a small number are made of mud or saliva.

Supported cupped nests of birds such as iora or oriental white-eye are located in the branches of trees and shrubs supported mainly from below.

The nest built by the sun birds and tailor birds are modified forms of the cupped nests.

The sunbird builds cupped nests that are suspended from above and look more like a small urn. There is an opening at the middle of the body of the urn for entry and exit. These are not supported from below.

The tailor bird’s nest is familiar to most. It folds together the two ends of a leaf and punches holes to keep them joined together using a variety of materials. In this image from my garden the tailor bird managed to get a lot of cotton fibres which were used not only to stitch the leaves together but to also form a soft cushion inside for the chicks to stay warm and cozy.

Retort shaped nest – Red-rumped swallow nest: Nests of swallows and swifts are amazingly diverse in terms of the materials used to build them. The edible-nest swiftlet makes its nest from its solidified saliva. This nest is on great demand in the market for making bird’s nest soup – a delicacy and as always the Chinese value it for its medicinal property.

The red rumped swallow’s nest is another kind of modified cup nest made of mud and is shaped like a retort. The nest is built first like an open cup which is then closed from top and the opening below is extended like a tunnel, the whole structure looking like a long narrow mud pot or retort. The birds mate inside the nest and it is believed such a structure will keep away other males from claiming the female. Both birds contribute to making the nest. Mud pellets are made from wet mud and painstakingly pasted on a substrate which could be a roof of a veranda where this nest in the photo was made. Secluded places such as under bridges or corner walls of buildings are generally selected. The inner part of the urn which is the egg chamber is lined with soft grass and feather for the chicks to develop.

Ornithologists are concerned that bird populations are threatened and in many cases dwindling due to lack of nesting spaces. Human dwellings these days are constructed with an intent to keep fauna out of co-dwelling with us. By chance if some find a place, humans are quick to sanitise them so that no pigeons or sparrows can come near us leave alone contemplate a nest.

In the outdoors, there is no thought given before cutting down those dead trees that are valuable assets for other animals. Thus artificial, man- made nests are now being provided to enable the bird species to reproduce. Making a bird nest can be great fun and in the process a service done to birdkind. Try making one and placing it in a suitable place in the school campus and then watch the drama that unfolds!

References
http://people.eku.edu/ritchisong/birdnests.html – Interesting page about Bird nests.

http://goldengateaudubon.org/conservation/make-the-city-safe-forwildlife/tree-care-and-bird-safety/types-of-bird-nests/ – Types of Bird nests.

http://nestwatch.org/ – All about nest watching.

http://indianbirds.in/pdfs/IB2.4_Palkar_Swallow.pdf – Red rumped swallow’s nest.

http://www.wikihow.com/Make-a-Bird-Nest – Some ideas for making nests.

Nest facts: Some like the Emperor Penguins do not build nests but incubate their eggs by keeping them between their feet, and covered by the folds of their skin. Some like the cuckoos are nest parasites and lay their eggs in nests built by the crows. According to the Guinness Book of World Records, the largest known nest was built by a pair of bald eagles: 9.5’wide 20’deep, weigh approximately 20 tons.

In the classroom
Activity: 1.Assess the health of an ecosystem using birds’ nests as indicators. 2. Observe and record a bird building a nest. 3. Make a nest for birds such as sparrows or babblers to nest.

1. There are many indicators that are used to assess the health of an ecosystem. An interesting activity one can carry out in schools is to use nests of animals or nests of birds as an indicator for determining the health of a habitat. A healthy habitat such as your school campus or the nearby park should surely have a few birds nesting! To investigate you require to collect facts first. About: the type of birds one is likely to see in one’s school/home; where and how and what type of nests would such birds make; whether the school is green enough to provide a habitat for birds to nest. The activity would also lead to learning a lot more about how to increase greenery and what type of plants can be grown and what can be done to encourage birds to nest. It is important to remember that if a bird’s nest is found, it is best to observe it from far and not go too close and stress the birds. With a little effort put in during the project to green the area, birds such as sunbirds, tailor bird, red vented bulbul, red whiskered bulbul, sparrows, crows, cuckoo, mynah could all be nesting in your school compound soon.

2. An interesting activity as a holiday project is to watch the birds build nests. If you see a piece of twig in a bird’s mouth be sure that it is taking it to build a nest. The birds are fast adapting to the changes in the environment. Do not be surprised to see a crow or myna carry a piece of plastic to build their nest. I saw a crow do just that recently. A tree outside your apartment is sure to have a crow’s or a myna’s nest.

3. You can make a small bird’s nest and fix on a safe place and surely a pair of sparrow or myna or a babbler or a warbler is sure to come to check it out. An old cardboard box can be covered with a plastic sheet and sealed completely from the front. Cut a small round hole at the back for the bird to enter and exit. Make sure that the small round hole you are making is a little towards the lower end and not in the centre. If you have an old football or if you can get one from the school, then cut it into two halves. Cover the outside of it with coconut fibres; line the inside with some cotton and leave it on the branch of a tree or a shrub. Observe to see if it gets accepted. Don’t be surprised if these nests are claimed by other animals instead of birds. You will witness interesting events and your holiday project will probably help you in ways you would not have imagined.

The author is a consultant for science and environment education. She can be reached at scopsowl@gmail.com.