Nav: Home

Lack of insects in cities limits breeding success of urban birds

May 18, 2020

Urban insect populations would need to increase by a factor of at least 2.5 for urban great tits to have same breeding success as those living in forests according to research published in the British Ecological Society's Journal of Animal Ecology.

Researchers at the University of Pannonia, Hungary and the University of Sheffield, UK found that providing high quality supplementary food to urban great tits, in the form of nutritionally enriched mealworms, can dramatically boost their breeding success.

"Urban nestlings had considerably higher survival chance and gained an extra two grams of body mass when provided with an insect-rich diet, an increase of 15% compared to the weight of chicks that didn't receive extra food. This is a substantial difference." said Dr Gábor Seress, lead author of the research. "This greater body mass when leaving the nest may increase the chicks' chance of surviving to spring and breeding themselves."

These beneficial effects of food supplementation were not seen in forest dwelling great tits where high quality nestling food is abundant. Although the free meals were also readily received by forest parents.

Reduced breeding success in urban bird populations is well documented but this study is the first to show that insect-rich supplementary food during nestling development largely mitigates these habitat differences. The findings indicate that food limitation in urban environments plays a crucial role in reducing the breeding success of insect-eating birds.

Dr Seress said: "Given the popularity of year-round bird feeding and the abundance of anthropogenic food sources in cities it might seem unlikely that urban birds have limited food. But quantity is not quality. Most songbirds require an insect-rich diet to successfully raise many and vigorous young, and urban areas generally support fewer insects than more natural habitats, especially caterpillars, which are key components of the optimal nestling diet for many species."

The authors say that artificially providing insect-rich food for birds in cities may not be the best solution. "Instead of directly supplying high-quality bird food to enhance urban birds' breeding success, we believe that management activities that aim to increase the abundance of insects in the birds' environment, would be more effective. Insects are the cornerstone of healthy and complex ecosystems and it is clear that we need more in our cities." said Dr Seress.

Increasing insect populations in cities in no easy task. The authors highlight that most urban green spaces are often highly managed which can reduce insect abundance. Modifying how green spaces are managed and encouraging practices like planting trees is likely to benefit both insect-eating birds as well as people.

In the experiment, the researchers studied great tits in nest boxes at urban and forest sites in Hungary, 2017. The urban sites were in the city of Veszprém with nest boxes placed in public green spaces such as parks and cemeteries. The forest site was three kilometres outside of Veszprém in deciduous woodland. At both sites there were broods that did not receive supplementary food to act as controls.

For the supplementary fed broods, the researchers provided nutritionally enhanced mealworms throughout brood rearing period on a daily basis, adjusting the amount in accordance to the brood size to meet 40-50% of food requirements. When nestlings were 15 days old (a few days from leaving the nest) the researchers recorded the size, weight and survival rate of chicks.

To estimate the amount of supplementary food consumed by the chicks and their parents, the researchers mounted small, hidden cameras on the nest boxes.

While the findings demonstrate that providing high quality additional food can boost breeding success, it is unclear to what extent this could increase population size and stability, further work is needed to explore this.

Further research into the reduced abundance of insects in cities is also needed. Dr Karl Evans, co-author of the research, said "There is a clear need for additional research to understand which of the many aspects that differ between urban and more natural areas causes the reduced abundance of insects in our cities and towns. This is essential in order to improve the habitat quality of urban environments for nesting birds".

British Ecological Society

Related Birds Articles:

Some dinosaurs could fly before they were birds
New research using the most comprehensive study of feathered dinosaurs and early birds has revised the evolutionary relationships of dinosaurs at the origin of birds.
If it's big enough and leafy enough the birds will come
A new study from the Cornell Lab of Ornithology highlights specific features of urban green spaces that support the greatest diversity of bird species.
How do birds understand 'foreign' calls?
New research from Kyoto University show that the coal tit (Periparus ater) can eavesdrop and react to the predatory warning calls of the Japanese tit (Parus minor) and evokes a visual image of the predator in their mind
How birds evolved big brains
An international team of evolutionary biologists and paleontologists have reconstructed the evolution of the avian brain using a massive dataset of brain volumes from dinosaurs, extinct birds like Archaeopteryx and the great auk, and modern birds.
Microelectronics for birds
Ornithologists and physicists from St Petersburg University have conducted an interdisciplinary study together with colleagues from Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences and the Biological Station Rybachy of the Zoological Institute of the Russian Academy of Sciences.
Birds of a feather better not together
A new study of North American birds from Washington University in St.
Not-so-dirty birds? Not enough evidence to link wild birds to food-borne illness
Despite the perception that wild birds in farm fields can cause food-borne illness, a WSU study has found little evidence linking birds to E. coli, Salmonella and Campylobacter outbreaks.
Birds are shrinking as the climate warms
After 40 years of collecting birds that ran into Chicago buildings, scientists have been able to show that the birds have been shrinking as the climate's warmed up.
Diving birds follow each other when fishing
Diving seabirds watch each other to work out when to dive, new research shows.
Why do birds migrate at night?
Researchers found migratory birds maximize how much light they get from their environment, so they can migrate even at night. 
More Birds News and Birds Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Warped Reality
False information on the internet makes it harder and harder to know what's true, and the consequences have been devastating. This hour, TED speakers explore ideas around technology and deception. Guests include law professor Danielle Citron, journalist Andrew Marantz, and computer scientist Joy Buolamwini.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at     You can read The Transition Integrity Project's report here.