If you live in a city, you might be forgiven for feeling the pressure of a more frantic pace of life. Fewer parking spaces, more pollution, less personal space, more traffic jams, roadworks, and noise, all contribute to higher stress levels, which often translates to aggression. And now, researchers have found evidence that this behaviour extends to song sparrows (Melospiza melodia), too.
But it comes with a surprising benefit to the youngest generation of city sparrows.
City-dwelling sparrows are superdads
In terms of numbers, there are fewer city-living song sparrows than in the countryside. However, the increased aggression observed in the males is attributed to a more urgent need to defend territories in urban areas.
But that increased aggression doesn’t mean the males neglect their duties as fathers. In fact, the researchers were surprised to find that the opposite may be true; they are more doting on their young and visit their nests more often than in rural situations.
"It turns out urban males are super males - able to defend their territories and care for their young,” says Dr Samuel Lane, a post-doctoral research fellow at North Dakota State University and lead author of the study published in Frontiers in Ecology and Evolution.
"Male songbirds in temperate zones are thought to reduce parental care when they are more aggressive. Yet in this study, we show that urban male song sparrows provided more care for their young," explains Lane. "Against our expectations, we found that they visited nests more frequently and were more successful parents than rural males.”
The early bird... feeds his chicks
The researchers carried out their studies at six sites across southwest Virginia, USA, that had been subject to recent urban growth, as measured across four breeding seasons. They found that not only did male sparrows visit their nests more often, but they also began feeding earlier in the day.
Despite the challenges of being a city bird, hatching and fledging success was observed to be higher in urban habitats. And even though brood parasitism (where one species will lay eggs in the nest of another) is typically higher in cities, the researchers observed that nest predation rates were lower, further contributing to the overall nesting success of these sparrows.
“It is often assumed that urban areas are more challenging for wild animals," Lane said. "Our study adds to growing evidence that certain species of songbirds even benefit from living in urban environments when there is sufficient green space for them to find food and nest locations."
The team hope ongoing research in this area will contribute to the construction of urban environments designed to offer improved support for wildlife.
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