The bird a nest, the spider a web, man pollution
There has been increasing concern over recent years about the fact that more and more species of birds are using rubbish as nest building material [1].
Obviously, one of the main reasons for this is necessity; uncontrolled human population growth and the associated spread of
urban landscapes results in the destruction of natural spaces and the subsequent loss of natural nest building materials [2] and so birds - like other animals - have to adapt to survive.
Unfortunately, not all bird species will be able to adapt to living in limited numbers in small isolated areas surrounded by people, cars, buildings, bright lights, etc. A big city lifestyle amongst the garbage isn't for everyone.
But some birds are at least giving it a go and they constitute one of the most common groups of urban animals:
"Their ability to fly allows them to move quickly between places to find
refuge, food, or water inside cities. Additionally, several bird species
are well adapted to urban areas because of their generalized diets (in
other words, they can tolerate the majority of food resources
available), large brains (allowing them to solve problems and use new
resources), non-specific requirements for nesting places (can nest in
the majority of available places), and small sizes (allowing larger
populations to survive on small amounts of resources)." [3]
However, whether using a diversity of waste materials - including plastic, wood, metal and rubber - as nesting material will prove to be beneficial or harmful to their survival in the long term remains to be seen. I suspect the latter [4]. For whilst there do seem to be some advantages to a nest constructed from artificial materials - for example, the nicotine found in fag ends is a known repellent against some parasitic insects - there are several negative consequences identified by researchers:
"For example, one negative effect of the use of garbage for nest building
could be an increase in the nest temperature when birds use plastic
bags pieces, a situation that could negatively affect an egg's embryo
development. Another negative effect may be an increase in nest
predation if, by being more conspicuous, artificial materials make nests
more easily detectable by visual predators. It is also possible to
expect a decrease in chicks' survival because plastic or nylon ropes may
attach and tangle around chicks in the nest, causing mortality." [5]
Let's just say that it isn't yet certain what the consequences will be of this new behaviour. But, having said that, I think we can agree that it makes the heart sink to read about baby birds reared amongst garbage and eating particles of microplastic.
Notes
[1] Such behaviour isn't new - indeed, it has been observed since the early 19th-century - but it is rapidly increasing as the natural environment becomes ever-more shaped (and polluted) by humanity.
[2] As two researchers in the field of urban ecology write: "The reduction in abundance of natural materials for nest building is
probably the force incentivizing species to use artificial materials,
which are becoming more, not less, available as human activities
increase."
See Josué Corrales and Luis Sandoval, 'Our Garbage, Their Homes: Artificial Material as Nesting Material' (December 2016). To read this text online, visit The Nature of Cities website: click here.
[3] Ibid.
[4] For a report by Anjit Naranjan in The Guardian (10 July 2023) on a newly published European study concerned with the safety of chicks being reared in nests constructed from rubbish, click here.
[5] Josué Corrales and Luis Sandoval, 'Our Garbage, Their Homes: Artificial Material as Nesting Material', op. cit.
For a follow up post to this one on crows and magpies ingeniously using human technology (anti-bird spikes) to protect their nests, click here.
