City Nature Challenge 2021: results and highlights | Citizen Science

A big thank you from the Citizen Science team to everyone who took part in City Nature Challenge this year! Between 30th of April and 3rd May over 300 people in London recorded 4,721 observations of 963 species – you can view everyone’s finds in the iNaturalist project

Highlights for me included the intriguing blind, white Ant Woodlouse (Platyarthrus hoffmannseggii) photobombing an observation of Yellow Meadow Ants (Lasius flavus) and a pair of beetles (Xylocleptes bispinus and Leptophloeus clematidis) which live in the stems of Wild Clematis (Clematis vitalba) – three observations in one! A sighting of the nationally vulnerable Green-winged Orchid (Anacamptis morio) in Upminster shows that London can support rare species too. 

Thanks are also due to the 323 people in London and around the world who helped identify observations during the City Nature Challenge DataBlitz. You can watch the City Nature Challenge DataBlitz chats with wildlife experts that the Bristol Natural History Consortium and I hosted, to learn more about how to get involved with identifying and recording nature near you. 

What did we find in London this year and how did it compare to 2020? Let’s look at the top observed species for each group: 

Top plant

The most observed plant this year was again Green Alkanet (Pentaglottis sempervirens). This plant is often considered a weed as it can spread rapidly, but the flowers are attractive to pollinating insects, particularly solitary bees. That’s excuse enough for me to keep some around! You can keep recording flowers in your garden after City Nature Challenge by signing up to Plantlife’s Every Flower Counts

Photograph of the a plant called Green Alkanet (Pentaglottis sempervirens).
Green Alkanet spotted during City Nature Challenge © Muki Haklay via iNaturalist CC BY 4.0 

Top bird 

Beating the last year’s Blackbird, 2021’s most observed bird in London was the Mallard (Anas platyrhynchos). These ducks are the ancestor of most domestic ducks and are a common sight in small garden and town ponds, as well as wilder places such as wetlands. There are often Mallards in the Museum Wildlife Garden pond. There are lots of different ways to get involved with bird recording and a good place to start is your own garden or local greenspace. Read our article City birds and how to watch them for tips and consider signing up to the BTO Garden Birdwatch. More tips on bird identification and recording are available in the Nature Challenge DataBlitz chat I had with bird expert Julian Hughes from the RSPB. 

Photograph of a male and female pair of Mallard ducks.
Male (front) and female (back) Mallards © Richard Bartz CC BY-SA 2.5 via Wikimedia Commons 

Top Mammal 

The grey squirrel (Sciurus carolinensis), one of our Species to Spot took the top spot again this year, as one of the few UK mammals active during the daytime this is not surprising. Despite being common it is still worth recording grey squirrels you see, particularly if you use the Mammal Society’s free Mammal Mapper app. 

Photograph of a grey squirrel in a tree.
Grey Squirrel spotted during City Nature Challenge © anneliesa CC BY-NC 4.0 via iNaturalist  

Top insect 

This year the most observed insect was the 7-Spot Ladybird (Coccinella septempunctata). This fairly large, native species of ladybird feeds mainly on aphids so is welcome sight for plant growers troubled by these sap-sucking insects. 

There are around 46 ladybird species in the UK but only 26 are readily recognisable as ladybirds, the others being small, brown, and easily overlooked. The bright colours and patterns of the 26 conspicuous ladybirds make them a good beetle group to get started with identifying and recording. The UK Ladybird Survey has a free guide [PDF 821KB] to the most common species and you can submit any you see (with photographs) on iRecord

More tips on getting started with beetle identification and recording are available in my City Nature Challenge DataBlitz chat with beetle expert Katy Potts from the Natural History Museum. 

Photograph of a seven spot ladybird.
7-Spot Ladybird spotted during City Nature Challenge By Victor Heng Public Domain via iNaturalist 

Top fungus or lichen 

The Golden Shield Lichen (Xanthoria parietina) took the top spot for fungus and lichen again this year. This lichen thrives in areas with high nitrogen and unlike some lichens is resistant to air pollution, so is common even in cities. It will grow on many different surfaces too, including tree branches, bricks, concrete and even plastic. During City Nature Challenge you found some lichens that indicate low pollution too, such as Evernia prunastri and Hypogymnia physodes, so maybe air quality in some areas of London is improving. 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 with other lichens and moss on a branch © helenfsc CC BY-NC 4.0 via iNaturalist 
It will also grow in artificial surfaces, such as a plastic! © Victoria J. Burton CC BY 4.0 via iNaturalist 

City Nature Challenge around the world 

City Nature Challenge takes place in cities across the world, in the UK this year 14 cities took part and over three thousand people made 62,260 observations of 3,103 species. Highlights included a spoonbill and a whinchat in Liverpool – birds rarely seen in this city. You can view all a map of observations in the UK during the City Nature Challenge on iNaturalist. Across the world, over 400 cities took part this year, exceeding 1 million observations on iNaturalist for the first time! You can find out more on what was found on the City Nature Challenge website.

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, for more on how data can be used read our blog post on the Field Studies Council Biodiversity Projects website. 

Want to take part next year? 

Keep an eye on the City Nature Challenge website for when the next Challenge will take place (usually the last weekend of April) and the City Nature Challenge UK website for which UK cities will be joining in. If you are interested in helping organise for your city region to take part in 2022 you can register your interest here.

City Nature Challenge is organised by California Academy of Sciences and the Natural History Museum Los Angeles County.