Category Archives: Biology

Your Dog’s Poop May Be Spreading Infections In The Air

Wow, it turns out pigeon poo in the air is not the only thing we need to worry about!

Recent research, published in Applied and environmental Microbiology, shows that the air in some Midwestern cities is populated by the same bacteria found in dog excrement. More from the article in Health Enclave: Your Dog’s Poop May Be Spreading Infections In The Air.

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Zoonoses, problems with pigeon-human proximity

In the last post, “Enjoying the Interactive Wildlife” we looked at some of the benefits of sharing our cities with feral pigeons. This post is about the drawbacks: pigeon-related zoonoses, or the diseases common between us. From the standpoint of the pigeons, the benefits outweigh the risks, they love living around us because humans = ample food sources and good architecture for roosting. Humans however, do worry about catching diseases from animals like pigeons. The animal we catch the most diseases from are other humans, but we do need to be aware of the diseases associated with pigeons since they live with us in our cities too.

People, statues and pigeons in Amsterdam

What we have learned so far is that the disease concerns around pigeons are focused on their droppings. New York City’s department of Health and Mental Hygiene puts out this informative fact sheet about the 3 health risks associated with pigeon droppings – in particular the cleaning of them – which they characterize as a small health risk.

1) Histoplasmosis – this is a disease caused by a fungus that grows in the soil and in concentrations of bird and bat droppings, which are high in nitrogen. It is a common disease – people living in places where the fungus grows naturally, such as the Ohio River Valley, are likely to have already had it, but not developed any symptoms. It is transmitted through airborne spores, not between people or animals. If symptoms develop, they are flu-like and include cough, headache, muscle aches, chills, shortness of breath. Mild cases go away without treatment, but severe cases need to be treated with anti-fungal medications. This disease can be very serious, even deadly, for people with compromised immune systems. More info.

2) Cryptococcosis – also a soil-dwelling, bird and bat dropping-loving fungus that can infect humans when they breathe in the spores. It is unlikely to get this infection, even by breathing in many spores. However, it is a concern because it can be very serious for people with weakened immune systems. It can even spread from the lungs into the brain and become deadly. 85% of Cryptococcosis patients are HIV-positive, according to the US Center for Disease Control (CDC). The CDC recommends that we avoid disturbing any accumulations of bird or bat manure so spores do not get released. Another interesting recommendation with regards to this disease comes from PubMedHealth “Practice safe sex to reduce the risk of getting HIV and the infections associated with a weakened immune system.” 

3) Psittacosis – a bacteria found in the droppings and nasal discharges in infected birds and spread through the air. It causes pneumonia-like symptoms and is sometimes called Parrot Fever because it infects mostly parrot-like birds. It is considered rare among humans and most of the reported cases are people who contracted it from pet birds. Pigeons can also get this disease and potentially spread it to humans through exposure to infected, dried droppings or respiratory secretions. I’m looking through the literature to see how often this happens. More on Psittacosis.

All three of these diseases are common to chickens and chicken manure.

And what about bird flu? Fortunately, that is one we don’t have to worry about with pigeons, as they have been found to be resistant to avian influenza.

Other things to be worried about? Maybe salmonella? Anything else? I’ll be continuing this pursuit of pigeon-related zoonoses and report back in a future post.

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The effects of pigeon cooing on the human mind

Crop milk production in pigeons is stimulated by the hormone prolactin. (This is the same hormone that stimulates milk production in mammals.) Interestingly, prolactin  produces an overall calming effect. Which fact leads neatly to a discussion of ‘calming’ and the effects of pigeon cooing on the human mind.

Predicated on the hypothesis that the human mind is pleasantly relaxed by the sound of pigeon cooing, we imagine the following experiment.

A range of volunteers, outfitted with electro-caps, is subjected to alternate recordings of circus music and pigeons cooing in the park.  Brain activity is recorded. The simplicity of the data imaging is humble, especially when juxtaposed against the spectacular imaging techniques driving today’s science. However simple, we find it illustrates the point.

To deepen our understandings, we ask you take the time to complete the brief survey below.

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Pigeon Milk, the wonder food

10 day old squab on a building ledge in New York City - image by Cutiepie Company

Lucky chubby squab. Fed the wonder food of Pigeon milk, they can double their size in 48 hours. In the book Pigeon, Barbara Allen also reports that, “Pigeon milk fuels what is one of the most explosive growth rates of almost any creature on earth”.  I’d like my next protein shake to be made of pigeon milk.

How to milk them? Fortunately, both the parent pigeons secrete the milk from their crops, which is located where the breast is. No nipples though, they use their throats like straws in reverse and their beaks serve as the delivery point into the mouths of their squab. So, I’m imagining a mechanical squab head bobbing around in the nest which is designed to accept the milk from the parent. This does sound ridiculous at first, but robotic cow milking machines are doing the same thing: mechanically milking an animal so humans can enjoy the nutritious results. Do check out this video of a robot milker in action on YouTube.  Pigeon milk might take longer to get, but it has more protein and fat than cow or human milk, so perhaps it would be worthwhile? [I can’t help but think of that recent, viral story about breast milk ice cream]. Thinking through the oddities of milking animals is enough to cause me to ask for almond milk in my next protein shake.

Breast milk ice cream on sale at a London ice cream parlour. Photograph: Graham Turner for the Guardian

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Naming the bird

“The pigeon will be doing stuff not just because it’s a pigeon, and it’s a Columbiform, and it’s from a family that has a small brain……It will be doing what it does partly because of that very specific regime of domestication that it went through for thousands of years.”[1]

In other words, the bird that interests us–the urban pigeon or city pigeon or house pigeon or feral pigeon or free-flying domestic or rat of the sky, your choice of street-speak–is a confusion of natural and artificial selection.

Here is a list of quasi-scientific names people have come up with to address this confusion and distinguish the “pigeon” from its wild rock dove (Columba livia) ancestor. All of which by the way are wrong according to the rules of taxonomic structure & biological typology–Columba livia forma urbana or Columba livia f. domestica or Columba livia var domestica or simply Columba livia var.[2]

In New York City pigeons are classified as livestock.


[1] Humphries, Courtney SUPERDOVE How the Pigeon Took Manhattan and the World. New York: Smithsonian Books, 2008. pg. 113

[2] Johnston, Richard F. and Janiga, Mariàn. FERAL PIGEONS. New York: Oxford University Press, 1995. pg.15

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The Mysteries of Pigeon Navigation – Radiolab Podcast

Pigeons are amazing. We still do not know how they manage to navigate home. Sight? Smells? Magnetic fields? All of the above?

This Radiolab podcast: Bird’s-Eye View, includes the story of a pigeon war hero who saved a town and it also explores the variety of experiments scientists have conducted to try to decode this navigational mystery – including putting blinding contact lenses in their eyes, strapping magnetic coils to their heads and transporting them inside smell-controlled boxes.

I wondered what the current state of research is on pigeon navigation and I found a report in the New Scientist about embedding devices in the brain of a pigeon that can record the electrical impulses in the pigeon’s brain at the same time as it records the GPS location. What the researches found is that the pigeon’s brain activity spiked up when they passed over landmarks like highways and coastlines.

Dubbed the Neurologger, this gadget simultaneously captures brain activity and GPS location of homing pigeons as they navigate over land and sea (Image: Alexei Vyssotski, University of Zurich)



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