Urban Air Pollution Leads to House Sparrow Decline in the UK

Sparrows are hardy little urbanites, yet scientists suggest that air pollution is killing these city-dwelling birds.

A new study out of Spain reveals that urban sparrows in the U.K. declined by an estimated 71 percent between 1977 and 2008. The birds are showing clear signs of stress that researchers link to the toxic effects of air pollution and a poor diet.

Almost everyone is intimately familiar with the house sparrow. The “urban exploiter species” lives all over the world, thriving and dominating in highly urbanized areas.

sparrow on cobblestones

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Sparrows “are well-adapted to urban life; therefore the decline of their populations in Europe represents an unexpected event,” notes the study. Rural sparrows, on the other hand, don’t show the same levels of stress and population decline.

Something about city life negatively affects sparrows. And wildlife scientists are now pretty sure it’s air pollution, coupled with a diet lacking in antioxidants such as carotenoids, vitamins and minerals. Past studies demonstrated that rural or suburban populations of other species, like blackbirds, showed higher concentrations of vitamin E and carotenoids than their urban counterparts.

Amparo Herrera-Dueńas of the Complutense University explained:

It is particularly bad for urban birds during the breeding season. When they are torn between allocating resources towards fighting the toxic effects of pollution or towards laying healthy eggs, both of which aren’t helped by their poor diet.

sparrows on a fence

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Herrera-Dueńas led the research team that analyzed blood samples from more than 200 sparrows. The scientists searched for signs of oxidative stress, which indicates the extent to which a given stressor may weaken the bird’s natural defenses. In the sparrows’ case, that stressor appears to be the double whammy of substandard diet and urban pollution. And the findings are sobering:

[T]he fragile oxidative stress balance of the urban House Sparrow, [is] promoted either by an excess of harmful free radicals due to pollution, or insufficient antioxidants due to scarce availability of dietary antioxidants, or both in urban environments. Therefore, birds need to invest resources in maintaining the oxidative stress balance, which is costly especially during the breeding season, when the constraints of antioxidants could entail negative consequences not only on the body condition of the individuals, but also on the viability and future fitness of their offspring.

If air pollution affects birds so noticeably, what’s the impact on other wildlife — or humans?

urban sparrow at cafe

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“If our cities are unhealthy for birds, which is what our study is suggesting, then as their neighbors we should be concerned because we are exposed to the same environmental stressors as house sparrows,” Herrera-Dueńas told The Express.

We already suspect that 20 percent of all Alzheimer’s and dementia cases may be caused by air pollution. In addition to its obvious impact on the lungs, other studies indicate that air pollution may be responsible for negatively affecting the heart and brain.

Is the house sparrow the proverbial canary in the coal mine?

Pollution reduction seems to be such a clear, simple and desirable goal. Sadly, despite this fact, we must continue to urge, wheedle and implore our elected officials to protect us. Will our legislators finally understand what’s at stake and act on it?

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76 comments

Renata B
Renata B12 days ago

Sparrow were so common in the past, now they are so rare. We are killing everyone and we think of being so intelligent!

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Glennis W
Glennis W15 days ago

Used to love the sparrows when on the farm Thank you for caring and sharing

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Glennis W
Glennis W15 days ago

Great information and advice Thank you for caring and sharing

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Glennis W
Glennis W15 days ago

Very interesting article Thank you for caring and sharing

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Glennis W
Glennis W15 days ago

So very sad Thank you for caring and sharing

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danii p
danii p15 days ago

Thanks for sharing.

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danii p
danii p15 days ago

Thanks for sharing.

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Carole R
Carole R16 days ago

Very sad.

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Michael F
Michael F16 days ago

Thank You for Sharing This !!!

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heather g
heather g16 days ago

Wheeeeezze - I agree.

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