City Nature Challenge 2022: Results and Highlights | Community Science

A round of applause for everyone that took part in City Nature Challenge this year! Between 29 April and 2 May, over 300 community scientists across London recorded a grand total of 4,436 observations of 1,087 species! You can view everybody’s findings in the iNaturalist project.  

Thanks are also due to the 338 naturalists in London and around the world that helped to identify the observations made during City Nature Challenge, validating over half of the observations in London to research grade records. With their quality assurance, these records can be used for the study of global urban biodiversity and conservation efforts. 

A particular photographic highlight from City Nature Challenge, London is this fantastic image captured of a Whirligig Mite (Genus Anystis) by user cordycept. iNaturalist shared this as their ‘observation of the day’ during City Nature Challenge! 

Whirligig Mite spotted during City Nature Challenge 2022 © user cordycept CC BY-NC 4.0 via iNaturalist 

So what did we find in London this year and how did it compare to previous records?  

Top plant and most observed species

The most observed plant and species overall for the 3rd year in a row is Green Alkanet (Pentaglottis sempervirens). Growing up to 90cm and usually thriving in damp or shaded areas close to buildings, they are often considered weeds. They have vivid blue flowers that are attractive to pollinating insects; particularly solitary bees, and they retain their green leaves even throughout the winter. 

Green Alkanet spotted during City Nature Challenge 2022 © Muki Haklay CC BY 4.0 via iNaturalist 

Most observed bird

Topping last year’s Mallard, 2022’s most observed bird in London is the Feral Pigeon (Columba livia var. domestica). Originally found wild in Europe, North Africa, and western Asia, pigeons have become established in cities across the world. They are abundant, with an estimated population of 17 to 28 million feral and wild birds in Europe alone and up to 120 million worldwide. 

Feral Pigeon observed during City Nature Challenge 2022 © Muki Haklay CC BY 4.0 via iNaturalist 

Most observed mammal

Unsurprisingly, the Grey Squirrel (Sciurus carolinensis), takes first place once again as the most observed mammal during City Nature Challenge both in London, and across the UK! Widely introduced to certain places around the world, the grey squirrel is regarded as an invasive species, particularly in Europe.

Grey Squirrel observed during City Nature Challenge © Victor Heng Public Domain via iNaturalist 

Most observed invertebrate

This year, the most observed insect/invertebrate was the Harlequin Ladybird (Harmonia axyridis). This artificially introduced species has taken the top spot from the native 7-Spot Ladybird (Coccinella septempunctata) in London and across the UK. There are around 46 ladybird species in the UK but only 26 are familiarly recognised as ladybirds because the others are small, brown, and easily disregarded.

Harlequin Ladybirds are native to eastern Asia, but were introduced to North America and Europe to control aphids and scale insects. In North America, this species is distinguished and known locally as the ‘Halloween beetle’, as they invade homes during October to shelter over winter. 

Harlequin Ladybird spotted during City Nature Challenge © Paul Cook CC BY-NC-ND 4.0 via iNaturalist 

Most observed fungus or lichen

A familiar favourite of City Nature Challenge – the Golden Shield Lichen (Xanthoria parietina) once again takes the top spot for most observed fungus or lichen. This lichen will grow on many different surfaces; from tree branches to concrete and even plastic. Unlike some lichens, it is resistant to air pollution,  so it is common even in urban areas. It is also worth noting that Oakmoss (Evernia prunastri) was observed in the Uxbridge area, perhaps indicating improved air quality. For more about lichens and what they can tell us about our environment read our article Nature and pollution: what lichens tell us about toxic air. 

Golden shield lichen observed during City Nature Challenge © user helenfsc CC BY-NC 4.0 via iNaturalist  
Oakmoss observed on the Brunel University Campus in Uxbridge during City Nature Challenge © user kathyvivian CC BY-NC 4.0 via iNaturalist 

Interesting observations

As well as shining a spotlight on the most observed species, records were made of some particularly intriguing and under-recorded species:

Chrysomela saliceti are new to Britain as of 2012, and subsequently found in several places in London with recently planted willows – its food plant. This species has a wide native range, occurring between Spain and the Russian Far East, including Central Asia and parts of Northern China but is quite rare. It will be interesting to see if it spreads further in London and other urban areas. 

Chrysomela saliceti observed during City Nature Challenge © Michael Geiser CC BY-NC 4.0 via iNaturalist 

Alder Leaf Beetle (Agelastica alni) – this is a native species but was extinct in the UK with no records between 1946 and 2003 but after accidental reintroduction, it appears to be increasing and spreading. 

Green Hairstreak (Callophrys rubi) – this is an under-recorded species in London and the only green butterfly in the UK. 

Green Hairstreak butterfly photographed during City Nature Challenge © user imaginesteve CC BY-NC 4.0 iNaturalist

White Letter Hairstreak (Satyrium w-album) – an elusive butterfly which feeds on elm, so declined rapidly after Dutch Elm Disease. 

Red Kite (Milvus milvus) – still not a common sight in London but increasing after its extinction from England in the early 20th century. Perhaps one day they will be as numerous as they were in Shakespearean London when they scavenged scraps from the streets?

A Red Kite observed during City Nature Challenge © user empressmoth CC BY-NC 4.0 iNaturalist 

White Helleborine (Cephalanthera damasonium) – an orchid with a conservation status of vulnerable, found in the chalk beech woodlands of South London. 

City Nature Challenge around the world

Across the world, over 400 cities took part this year, reaching over 1.6 million observations! You can find out more on what was found on the City Nature Challenge website

In the UK alone, 14 cities took part and over three and a half thousand people made 55,871 observations of 3,607 species – what an incredible contribution to urban biodiversity mapping! You can view a map of observations in the UK during City Nature Challenge on iNaturalist

We especially commend our community science colleagues over in Ukraine, where 7,867 observations were made by 240 people of 1,698 different species. Although conservation efforts and protected areas are at risk, scientists and naturalists have continued to prevail in attempts to document the nature that thrives there.

Particular notability should be given to a single record of the endangered Przewalski’s Horse (Equus ferus ssp. Przewalskii), made during City Nature Challenge in Northern Ukraine by zoologist Vasyliuk Oleksij. 

Przewalski’s Horse observed in Ukraine during City Nature Challenge © Vasyliuk Oleksij CC BY 4.0 via iNaturalist 

Other magnificent observations made around the world throughout City Nature Challenge include the critically endangered Eurasian Hamster (Cricetus cricetus) in Vienna, Austria, an endangered Dusky Shark (Carcharhinus obscurus) off the coast of Sydney, Australia, and a Bolivian Racer (Philodryas boliviana) in La Paz, Bolivia.

What happens next?

Data collected during City Nature Challenge is available for anyone around the world to use for research and conservation. In London we work with our Local Environmental Records Centre (LERC), Greenspace Information for Greater London (GiGL) to maximise the usefulness of the data. 

Next year’s City Nature Challenge will take place 28 April –1 May 2023. Keep an eye on the City Nature Challenge website to find out if your city is taking part. If you are interested in helping organise for your city region to take part in 2023 you can register your interest here.