by Shalini V – One day, while gazing at the lawn, I noticed something that stirred my thoughts. I saw a rock pigeon, picking sticks to build its nest. The pigeon picked a stick. Then, in less than a minute, dropped it, picked another, dropped it again, and finally selected one after rejecting four sticks. Now the question – Why did the pigeon reject the other sticks? Studies show that birds choose nesting materials based on structural properties, but how do they know it? Do they have the sensory processing to detect properties like bulk modulus, ultimate tensile strength, thermal conductivity or shear modulus just by touch or smell? Engineers use different tests to check a material’s suitability as a construction material, but how do they do it? Astonishing!
Their way of selecting and choosing construction materials like sticks, leaves, mud (swallows), saliva (swifts), spider webs, feathers, caterpillar silk (hummingbirds, vireos), plastics, hair, fur and also snake skin is amazing and mysterious. But even more amazing is the architecture of the nest.
Since ancient times, birds have been admired for their flight, migration, their calls, communication and their nesting behavior. A nest may look simple, just a pile of leaves, sticks and other materials, but the material at each section of the nest has a different property. The outer section is usually hard and the materials used are thick and durable, The inner sections are cushion-like and provide warmth so soft and thin materials with good thermal properties are used.
A weaver bird in Uda Walawe, Sri Lanka. Photo by Davida de la Harpe.
Talking about their construction, we cant miss the weaver bird’s nest. A peek into weaver bird’s nest will take us to a beautiful room to hold the young ones, perfect for incubation, Isn’t it simply a jaw dropping architecture!
Some birds even know to STITCH! Turn to tailor bird’s nest with leaves woven together. Now how did they learn that?
Common Tailorbird Orthotomus sutorius nest in Hyderabad , India. Photo by JM Garg
These are just two types of nests. There are many more types of nests in nature like ground nests (ostrich, emu etc) and floating nests to name few. A bird’s knowledge doesn’t stop with construction – they are also aware of the importance of cleanliness. The young leaves and cedar barks you find are there for a purpose, they are natural pesticides and protect the nest and young ones from pests and infection.
A nest with its owners and young ones, despite being a peaceful retreat to us, opens a new area to be discovered, explored, admired, inspired, loved and appreciated! And my first question still awaits to be answered, why did the pigeon reject the four sticks?
References:
- Biddle L, Goodman AM, Deeming DC. 2017. Construction pattern of Bird’s nest provide insight into nest-building behaviors. PeerJ. DOI 7717/peerj.3010.
- Bailey IE, Kate V. Morgan KV, Marion Bertin M, Simone L. Meddle SL and Healy SD. 2014. Physical cognition:birds learn the structural efficacy of nest material. Proceedings of the royal society B. http://dx.doi.org/10.1098/rspb.2013.3225.
- https://web.stanford.edu/group/stanfordbirds/text/essays/Nest_Materials.html
NICE 