02 — Seasonal Watch: Autumn Arrivals
Autumn is not only things ending. Some of the most interesting wildlife of the year is only just arriving.
By the Bosk team ·
Ask most people what migration looks like and they will describe a nature documentary: geese against a sunset, a coastline crowded with waders, something that happens somewhere else, to someone with better binoculars.
What happens in an ordinary park or garden in autumn is quieter. And it is happening whether or not anyone is there to see it.
What is arriving
Across much of north-west Europe, autumn is when birds from further north and east come in to spend the winter. Redwings and fieldfares are the classic examples: winter thrushes that arrive from Scandinavia and beyond, often first noticed as a thin call overhead before anyone sees the bird itself. Berry bushes, hawthorn and rowan quickly become busy. Even blackcaps, a bird many people think of as a summer visitor, can turn up at garden feeders in winter.
If you live somewhere else, the details change but the pattern does not. Autumn rearranges who is where. Some species are leaving, some are passing through, and some are only just getting here.
Two populations in one tree
This is what makes autumn different from other seasons. In the same park, on the same day, you can find residents settling in for the colder months and visitors using the same trees as a temporary stop. One oak can hold a nuthatch working the bark in its usual spot and a bird that arrived overnight and will move on in a day or two. Same tree. Two completely different jobs.
That overlap is short. By midwinter the cast has settled, and the park holds its winter residents until spring.
Migrations underway around the world
Your park is one small stop on much bigger journeys. Here are a few happening right now.
### Cranes: the sound before the sight
Across Germany this month, common cranes are moving from breeding grounds in Scandinavia and the Baltic toward Spain and France. They travel in V-shaped skeins, and most people hear the trumpeting call before they see anything. Tens of thousands rest at well-known stopovers such as Linum in Brandenburg, not far from Berlin, feeding in fields by day and roosting in shallow water at night.
### Arctic terns: the longest commute
An Arctic tern breeds in the far north and spends the northern winter in the waters around Antarctica. Tracking of terns from Greenland and Iceland found a round trip averaging about 70,000 km a year, and up to around 80,000 km for some birds, among the longest known migrations of any animal. By late October most have already left Europe and are far into the Southern Ocean, where it is summer.
### Bar-tailed godwits: one flight, no landing
Bar-tailed godwits from Alaska head south in autumn for New Zealand and eastern Australia. Satellite-tagged birds have flown more than 11,000 km non-stop over the Pacific without eating, drinking or resting. One female flew about 11,700 km in over eight days, and in 2022 a tagged male flew about 12,000 km in 11 days.
### Monarch butterflies: a journey no single butterfly makes twice
In North America, eastern monarchs are flying south toward the oyamel fir forests of central Mexico, roughly 4,000 km or more. It takes three to four generations to complete the yearly cycle, and the late-summer generation that flies to Mexico has never made the trip before. The migratory monarch is now listed as endangered by the IUCN, so recorded sightings matter.
### Southern hemisphere: arrivals, not departures
While the north heads south, it is spring in the southern hemisphere and migrants are coming in. Short-tailed shearwaters return to their burrows around Tasmania and southern Australia within days of each other each late September to October, after a long journey from the Bering Sea region. Population estimates run from about 20 to 30 million birds.
What to look and listen for
- Thin, high calls overhead, especially at dusk. Often the only clue that something is passing through.
- Flocks working through berry bushes and fruit trees, stripping them faster than you would think.
- Fungi after rain, on lawns, log piles and the bases of trees.
- Nests that were hidden all summer, now visible in bare branches.
- Leaves doing their last job: turning, falling, and becoming shelter for insects over winter.
None of this needs a dawn start or a nature reserve. It takes about ten minutes of paying attention on a walk you were already taking.
Why the ordinary sightings count
One sighting of one bird does not tell you much. A pattern does. When it arrived this year, whether that is earlier or later than last year, which parks and corridors birds actually use to move through a place. No single walk can show that. Lots of ordinary walks, noticed and recorded, can.
What is the first sign of autumn you notice where you live?
Try this outdoors
Pick one spot near you and give it ten quiet minutes. Note three living things you have never really looked at, then see what you can learn about them.
Read about the woodland, urban or other habitats, see what is in season now, or join the beta. Want to see what else Bosk can do? Read about the platform.