IT is a newly defined “billion club”, but it has nothing to do with finance. A new study has identified four birds that each have a population of more than a billion, as birdwatching enjoys a boom.

 

Which birds?

The study by researchers at the University of New South Wales in Sydney, Australia, determined that there are four bird species in the "billion club"- the house sparrow, with 1.6 billion, the European starling at 1.3 billion, the ring-billed gull at 1.2 billion and the barn swallow at 1.1 billion.

 

By contrast?

Their research also found that although earth is home to around 50 billion wild birds in total, most species are very rare, with 1,180 species numbering fewer than 5000 birds each.

 

Including?

Species such as the Chinese Crested Tern, Noisy Scrub-bird and Invisible Rail.

 

Alarm bells are ringing?

Nearly. Associate professor Will Cornwell, an ecologist at UNSW Science and co-author of the study, warned: “We’ll be able to tell how these species are faring by repeating the study in five or 10 years. If their population numbers are going down, it could be a real alarm bell for the health of our ecosystem."

 

How did they establish the numbers?

The researchers took scientific data collated by bird conservation organisations and combined it with data from eBird, an online index of bird observations that includes more than 800 million contributions from amateur birdwatchers. They then cross referenced and refined it all to create an algorithm that estimated the population sizes for species.

 

Conservation is the aim?

Study co-author, Dr Corey Callaghan, who is now based at the German Centre for Integrative Biodiversity Research, hopes the findings will aid efforts to save birds at risk of extinction, pointing out a need to establish why some species are rare - if it is due to human impact, such as deforestation, or because some have evolved to populate certain areas. He said: “Quantifying the abundance of a species is a crucial first step in conservation. By properly counting what's out there, we learn what species might be vulnerable and can track how these patterns change over time.”

 

Birdwatching is taking flight?

It is a hobby that first grew in popularity in Victorian era Britain - that more serious participants are likely to refer to as “birding". In lockdown, though, more Brits have been turning to the pursuit than ever before - an online OnePoll survey of 4,000 people this month found 16% began birdwatching during the pandemic.

 

Hear my song?

A survey commissioned by the RSPB in January found 63% said watching the birds and hearing their song had added to their enjoyment of life in lockdown.

 

Meanwhile, in Philadelphia?

Residents are dimming their lights in a bid to save some of the 100 million birds that fly through the US city on their semi-annual migration each year. Nearly 20 tall structures are taking part in “Lights Out Philly,, a voluntary scheme in which external and internal lights are turned off or dimmed through the night in May to prevent birds from accidentally flying into the tall buildings. Bird Safe Philly organised the effort after more than 1,000 dead and injured birds rained down on Philadelphia last autumn.