Highlights from City Nature Challenge 2020 | Citizen Science

What were your highlights from the City Nature Challenge this year? Although I missed taking part in a public BioBlitz at the Natural History Museum, I enjoyed my own mini BioBlitz in my little London garden – making 99 observations and managing to identify 80 different species. My favourite find was a tiny Bethylid wasp which was the first one I have ever seen. These wasps are just a few millimetres long and are known as ‘flat wasps’ because of their squashed appearance. They are parasitoids of beetle larvae or moth caterpillars.

Bethylidae wasp
The Bethylid wasp I found, too tiny to do justice with my camera. Photograph by VJ Burton.

An adder (Vipera berus) was seen during the City Nature Challenge: London. Adders are one of the three native species of snake in the UK and our only venomous species, although fatalities from bites are exceptionally rare. All native snakes in the UK are protected and are in decline to loss and fragmentation of their habitat, especially in urban areas, so seeing one in London is very special. For more on British snakes read the Natural History Museum article Should we be scared of British snakes?

In Bristol a grey seal (Halichoerus grypus) was seen several kilometers up a river in the middle of a city park! In the UK there are two species of seal – the common (or harbour) and grey. Around half of the world’s population of grey seals is found around Britain and numbers seem to be recovering now they are better protected. A grey seal inland in Bristol is a very rare sight though and perhaps a result of quieter urban areas as a result of the coronavirus lockdown. In Birmingham there was a lucky photograph capture of a weasel (Mustela nivalis) and further afield in Calgary, Canada a moose (Alces alces) was sighted – a very unusual observation within the city itself.

Grey seals on a beach in Norfolk
Grey seals in their usual habitat on a beach in Norfolk. Photograph by Duncan Harris via Wikimedia Commons (CC BY 2.0)

London’s top observations

A total of 1,069 species were seen in London during the City Nature Challenge this year. Out of the top 10 overall most observed there were eight plants and two birds. The most observed in each category were:

Top plant – green alkanet (Pentaglottis sempervirens)

This bristly plant has striking bright blue flowers which are attractive to bees and other insects. The ‘green’ part of the common name of this plant, as well as the specific name (sempervirens = always green) refers to how the leaves stay green in the winter. Green alkanet was introduced to the UK hundreds of years ago for the rich red that can be obtained from its roots. Today it is often seen as a weed as spread thickly in damp gardens but I keep some around for pollinating insects. How good is your garden for flowers? Count flowers in your lawn with Plantlife’s Every Flower Counts this May.

Green alkanet growing in London
Green alkanet flowering in London. Photograph by Emőke Dénes via Wikimedia Commons (CC BY-SA 4.0)

Top bird – blackbird (Turdus merula)

The most observed bird for London and for the UK as a whole during 24-27 April was the blackbird. Blackbirds are a species of thrush – despite their name only adult males are black, females and juveniles are brown with spots and streaks on their fronts. They are one of the most common birds in urban areas and regularly make the top 5 of the RSPB Garden Birdwatch. For more on urban bird-watching read our article City birds and how to watch them.

Male blackbird
Male blackbird. Photograph by Ruben van Kuik via Wikimedia Commons (CC BY-SA 4.0)

Top mammal – grey squirrel (Sciurus carolinensis)

The familiar grey squirrel was by far the most observed mammal in London’s City Nature Challenge, with 42 observations. Grey squirrels were first introduced to Britain in the 1870s and spread rapidly, largely displacing the native red squirrel (Sciurus vulgaris) in mainland England. Grey squirrels are largely animals of deciduous woodland, feeding on large tree seeds such as acorns, beech and hazelnuts; but adapt well to urban areas, often taking food from bird feeders. You can download the Mammal Society’s free Mammal Mapper app to record your sightings of grey squirrels and other mammals in the UK.

Grey squirrel in a London park
Grey squirrel in a London park. Photograph by Bigfoot, via Pixabay (Public Domain)

Top insect – speckled wood butterfly (Pararge aegeria)

As its name suggests, this butterfly is associated with woodland, but it can also be found in gardens if there are sufficient shrubs and trees to provide the shaded areas it prefers. Unlike many butterflies in the UK the population of this species is increasing. You can help monitor butterfly populations by recording which you find in your garden with the Butterfly Conservation Garden Butterfly Survey.

Speckled wood butterfly
Speckled wood butterfly. Photograph by Wildlife Terry, via Flickr (Public Domain)

Top fungus or lichen – golden shield (Xanthoria parietina)

Lichens are a mixture of a fungus and an algae. The golden shield lichen is a relatively distinctive lichen which is an indicator of areas of high nutrient content, such as were birds perch. The deep yellow-orange colour is caused by the pigment parietin which acts like a sunscreen, protecting the lichen from UV-B light. In shadier areas the lichen is greener in colour.

Xanthoria parietina on a roof
A rooftop well covered with golden shield lichen. Photograph by NearWildHelen (Public Domain)

The City Nature Challenge maybe over for this year but nature can be found whenever you are, all year round. Share your nature finds with us on on Twitter @NHM_CitSci.

One Reply to “Highlights from City Nature Challenge 2020 | Citizen Science”

  1. Thank you for the brilliant article, the photos are amazing and the information is really interesting. I will share this with some of my colleagues.

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