It’s fascinating how resourceful birds can be when it comes to nesting. In this post, we look at some of the most unbelievable items they’ve been known to incorporate in building their nests. From Barbie dolls to cable ties, birds have adapted to the human presence in urban areas with apparent ease.
Anti-bird Spikes
Perhaps one of the most ironic examples is that birds (particularly magpies and crows) have been documented stealing anti-bird spikes designed to deter them and using these spikes to build their own nests. This shows a remarkable level of adaptation.
This behavior has been observed in various European cities, including those in the Netherlands, Belgium, and Scotland. Magpies seem to use the spikes as a defensive measure, incorporating them into the outer layer of their nests to deter predators, while crows tend to use the spikes for structural support within the nest.
Birds are actively removing the spikes from buildings, leaving behind traces of adhesive. This is particularly risky for the bird, and there have been instances where they have been pierced by the spikes. Scientists are not sure if they are choosing them because of a lack of natural material or simply because they are available.
Plastic
Birds often utilize readily available materials, which in urban environments can include pieces of plastic bags, wrappers, and other discarded items. Birds use plastic because it often mimics natural materials like twigs or fibers.
It might look amusing and harmless, but as we all know, plastic is not a benign material. Its fairly indestructible nature means if it entangles birds and their chicks, they are in big trouble. Plastic pieces and particles can also be ingested, causing internal injuries or poisoning. Lastly, plastic bags or strips can disrupt nest temperature regulation.
This pigeon was photographed using cable ties as the primary building blocks of its nest.
The image below of a coot in Amsterdam was studied and the nest was found to contain plastics dated up to 30 years ago.
Black Kites in Spain decorate their nests with plastic, and research suggests this behavior serves as a visual signal of their strength and ability to defend their territory, acting as a keep away signal to other kites.
Studies in Doñana National Park in Spain have shown that they use white plastic in their nests, with the most robust nests displaying the most plastic. The researchers found that birds with more plastic in their nests were better fighters, more successful at defending their territory, and produced more offspring. The strongest and fittest kites, typically in their prime reproductive years (around 7-12 years old), used the most plastic. Younger and older birds used less or no plastic.
The birds scavenge for white plastic and place it in their nests alongside their eggs. The researchers believe that the plastic serves as a social test, where kites are checking each other’s honesty and ability to defend their territory. The white plastic is not a camouflage strategy, as the birds that decorate their nests always lay eggs, while those that don’t sometimes fail to breed.
Cigarette Butts
Birds, particularly species like House Finches and House Sparrows (pictured above), collect discarded cigarette butts from streets and other areas. They often pull apart the cigarette filters, extracting the fibrous material. The birds then incorporate these fibers into the lining of their nests. This material is woven in with other nesting materials like twigs, grasses, and feathers.
Research indicates that the primary reason birds use cigarette butts is to repel ectoparasites, such as mites and ticks. Nicotine, a substance present in cigarette filters, acts as an insecticide, deterring these pests. Studies have shown that nests containing cigarette butt fibers have fewer ectoparasites.
It is also possible that the fibrous material within the cigarette butts also provides a level of thermal insulation for the nest. This behavior highlights the birds’ ability to adapt to human-altered and polluted environments.
However, while nicotine may repel parasites, it is also a toxic substance and there are concerns that exposure to nicotine and other chemicals in cigarette butts could have negative health effects on birds and their chicks. Studies have shown that nests with more cigarette fibers also had chicks with more genetic issues.
Clothing Items
Underwear, socks, and other articles of clothing have been found in bird nests. In urban and suburban environments, fabric scraps, threads, and other clothing fibers are readily available. In the photo above a bird has actually built its nest within a pair of underwear.
Many fabrics provide softness and insulation, which are desirable qualities for a nest. Birds instinctively seek out these kinds of fibrous materials, and clothing scraps can sometimes resemble natural fibers.
Threads and yarns are the material most commonly found in nests, as they are easily woven into the structure. Pieces of old clothing, rags, and other fabric scraps may also be used. While not strictly clothing, dryer lint is a byproduct of clothing and is sometimes used, though it’s often discouraged.
Threads and long fibers can easily entangle birds, especially nestlings, leading to injuries or death. Clothing also often contains dyes and chemical treatments that can be harmful to birds. They cannot distinguish between natural and man-made and synthetic fibers may not break down naturally and can create long-term hazards.
While birds may use these materials, it’s generally not recommended to provide them intentionally. Natural nesting materials, such as twigs, grasses, and leaves, are always the safest options.
Toys
Birds, especially those in urban environments, are highly adaptable and will use available materials. This means that if toys are present, they may be incorporated into nests. Examples include plastic toy pieces (like parts of dolls or action figures), toy stuffing, small, colorful plastic toys like Lego. There have been documented cases of birds using doll hair, and even parts of dolls, within their nests. This is a very visual example of how birds will use what is available.
The reasons for using toys vary from availability (the toys are simply present in the bird’s environment) to visual appeal. Brightly colored toys may be attractive to birds. Certain toy materials may also provide insulation or structural support.
Plastic pieces are often durable and readily available, making them potentially reliable and secure nesting materials. However, plastic can pose risks, such as entanglement and ingestion.
Metal items
Species like magpies (nest pictured above) and crows, which are known for their intelligence and adaptability, are the most frequent users of metal wire. Metal wire, being strong and durable, can provide a sturdy framework for the nest. Historic reports of birds using barbed wire as a defense against intruders demonstrate that the use of metal materials is not a new phenomenon.
It seems that birds have long been adapting to the materials available in their environment, especially in urban areas. They are finding creative ways to use these materials to enhance the structure and defense of their nests.
Hair
It’s very common for birds to utilize hair, both animal and human, in their nest building. Hair, especially fur, provides excellent insulation, helping to keep eggs and chicks warm, and it creates a soft, comfortable lining for the nest. Shed hair from animals and humans is readily available in many environments. The hair can also help to bind other nesting materials together, adding to the structural integrity of the nest.
Birds often collect shed fur from pets like dogs and cats. In rural environments, they may use fur from wild animals like deer, bison, or squirrels. There are even cases of birds taking hair directly from living animals. There is a term for this: Kleptotrichy. Birds will readily use human hair, and this can include hair from hairbrushes, haircuts, or even just shed hair found in the environment.
Although hair is natural, it is important to remember that human and pet hair may have chemicals present. Hair treated with harsh chemicals, such as flea and tick medications or hair dyes, could be harmful to birds. Furthermore, long strands of hair can pose an entanglement risk to birds, especially chicks.
Final Thoughts
Birds utilizing unusual and non-natural materials for nesting is a complex issue stemming primarily from their adaptability in human-altered environments. In urban and suburban areas, human-made materials are often more abundant than natural ones. Birds are opportunistic and clever and use what’s readily available. They can adjust their behavior to utilize new resources.
Some materials, like plastic or metal wire, can provide structural support, insulation, or even defense, while other materials like cigarette butts, provide pest control. Further, brightly colored items may be used for nest decoration or to signal territory.
While we can admire the birds’ ingenuity, it is not all good news. Threads, wires, and plastic can entangle birds, especially chicks, causing injury or death. Birds may also ingest plastic or other harmful materials, leading to internal injuries or poisoning and materials like cigarette butts or chemically treated fabrics can expose birds to toxins.
