Signs of autumn: What to look out for in the natural world

Fly agaric mushrooms

As autumn draws in there are some big changes under way in the natural world.

Welcoming the changing seasons

Plants and animals alike put on a final show before the cold winter months so it's a great time to get out and enjoy nature's seasonal sights.

As well as enjoying the spectacle, the public can also contribute valuable seasonal research data. With the help of "citizen science", researchers can use enthusiasts' recordings of natural phenomena to see how seasons change over time.

As part of the Nature's Calendar survey, experts at The Woodland Trust and the Centre for Ecology and Hydrology (CEH) want observation data to help them track how the seasons are developing across the country.

Buglife, the Invertebrate Conservation Trust, also has year-round public surveys that will improve the charity's understanding of wildlife behaviour throughout the year.

Here are some of nature's big events that can be reported on from September onwards.

Animal behaviour
Common dormouse Dormice gorge on fruit and nuts in autumn in preparation for hibernation

Falling temperatures trigger mass migrations as birds seek sunnier climes. The favoured winter destination of northern European birds is Africa. Nature's Calendar is interested in tracking this phenomenon so keep a record of the birds leaving your area and submit the findings. Nature's Calendar also wants to know about winter arrivals like redwing or fieldfare.

The British Trust for Ornithology is similarly seeking migration and distribution reports for the BirdTrack survey.

Squirrels and jays burying acorns aren't the only British inhabitants to display different behaviour in the run-up to winter. Invertebrates such as butterflies and ladybirds may venture indoors as they seek warm spaces in which to sleep through the colder months.

Hedgehogs, dormice and bats gorge on fruit, nuts and insects respectively, to build up stores of body fat in readiness for hibernation. Dormice have a very particular way of chewing hazel nuts, leaving distinctive tooth marks.

As a species under threat, it's important to know where they still survive. It's a lot easier to find nibbled nuts before leaves really start to fall so early autumn is a great time to join the People's Trust for Endangered Species's great nut hunt.

Stags battling Autumn is an important time of year for deer seeking mates

Autumn is the busiest time of year for many animals, including deer, boar and bats, which are all seeking mates. For larger mammals it can be a violent, dramatic affair - stay a good distance from the action so you don't disturb them.

Rather than physical competition, bats serenade potential mates. It's possible for the human ear to hear these songs but a bat detector is more reliable. Early in the autumn swarms of Daubenton's and Brandt's bats can be seen around the entrances to tunnels and caves, singing for the attention of females inside. Help scientists learn more about bat behaviour by taking part in a variety of surveys with Bat Conservation.

Turning leaves
Horse chestnut tree leaves in autumn The timing of leaf colour-change can vary depending on location

As the sunlight wanes trees stop producing chlorophyll for photosynthesis and leaves begin to change colour. The timing of this colour change varies by species and location. Nature's Calendar wants recordings of leaves starting to tint and which species transform first.

Over the past few years, the leaves of horse chestnut trees have been turning earlier than expected. In many cases this isn't down to an early autumn but because of an infestation of moth larvae.

The horse chestnut leaf miner (Cameraria ohridella) lays its eggs deep in the leaves and the leaves quickly turn brown once larvae start feeding in them. Scientists are interested to know where these moths are, so register any sightings of horse chestnuts turning early in the season in the alien moth survey.

Later in the season, you can also report the first full leaf tint (when every leaf turned yellow, brown or red), the first leaves falling and the first bare tree to Nature's Calendar.

Fruit, nuts and seeds
Blackberries ripening Blackberries ripen from August to early autumn

In autumn plants look to the future, dispersing their seeds through a number of techniques so that they can spread and grow next spring.

From September onwards you're likely to see lightweight seeds like sycamore "helicopters" travelling by air. Prickly specimens such as beech nuts hitch a ride on animal coats.

Acorns appeal to mammals and birds alike as both squirrels and jays bury them to provide meals through the cold winter.

Many plants use fruit as a highly effective method of seed dispersal. For example, blackberries are eaten by everything from birds, to foxes and wasps.

If you are out foraging for fruit, record your first ripe fruit sightings for Nature's Calendar.

As well as the first sightings, surveyors are interested in whether it's been "a good year for berries". It is more difficult to make these kinds of assessment but if you are a seasoned fruit-picker, you might be able to tell whether there are fewer or more berries than in previous years.

Fly agaric mushroom Fly agaric mushrooms make an iconic sight in the UK's woodlands and heaths

Through a combination of the summer warmth and autumnal damp, there's an explosion of mushrooms starting in September each year. Mushrooms are the fruiting part of fungi and appear throughout autumn to spread their spores and establish new kingdoms.

Be aware that some species of mushroom are fatally poisonous. When looking for mushrooms, use a reliable field guide and be completely certain of a mushroom's identity before touching any. A better option is to join a guided mushroom walk and just enjoy the sights.

You can also record the first iconic red and white fly agaric of the season to Nature's Calendar.

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