I've always thought that 21 June is the summer solstice, marking the longest day of the year and the official start of summer. It's a date embedded in my pysche for one obvious reason, being my birthday. As a child I remember it as a date that was always sunny. I'm sure that must be down to the rose-tinted spectacles as more recently it seems to have date afflicted with rain - as today.

I was surprised, therefore to have a stream of people pulling me up on Twitter when I refered to today as the longest day, because this year the solstice actually fell on 20 June - as indeed it apparantly does every leap year. It just goes to show that you're never too old to learn new facts. It was at least comforting to know that the difference is only one second, but it does mean that the days start to shorten from here on in.

As ever, nature is ahead of the game, and the first "autumn" migrants are already appearing. These are better referred to as return migrants, and are already heading south from their Arctic breeding gounds. The first return migrants, as usual, were spotted redshanks, which appeared about on cue over the weekend. These will almost certainly be females which have laid their eggs and left the males to rear the chicks. They are in their stunning white-spotted black breeding plumage. A few spotted redshanks should now be visible somewhere on the Scrape or Levels every day until September - providing we get enough rain to prevent them drying out, and not too much that the causes flooding.

Other signs of the changing season include an Arctic tern on South Scrape - again, probably returning south having failed to breed elsewhere. We can expect the first roseate terns anytime now, too. Perhaps more dififcult to classify is the knot that's also on South Scrape today. Is that heading north or south? Two spoonbills remain on North Scrape and are probably non-breeding birds from Holland.

Of course, another sign of the arrival of summer is the sight of young birds around the reserve. The flooding in May has affected the timing for some species, with fewer gulls nesting on the Scrape, but the first young marsh harriers, known as flappers, are beginning to fledge from their reedbed nests. A few female bitterns are already feeding chicks, and more should hopefully hatch any time. The stone-curlews behind the visitor centre finally hatched two chicks earlier this week. Being mobile, they're generally wandering out of site so have become much more difficult to see. Similarly, the glossy ibis (or possibly still two) on the Levels are hard to spot due to the long grass.

Mid June always sees the arrival of late summer migrants from southern and eastern Europe too, and this week was no different. A male red-backed shrike was at Island Mere on Sunday, and a bee-eater flew over the visitor centre on Monday afternoon. The biggest surprise, though, was a large white-faced darter (also known as a yellow-spotted whiteface) that was found just off the reserve near our boundary with the National trust at Dunwich Heath on Tuesday. It may have been present for a couple of days and is the first ever British record of this lovely dragonfly. I was away at the time so missed it, but I'm familiar with species, having seen many in Poland last year.

When the weather is suitable, late June is a great time to look for dragonflies, including Norfolk hawkers, and butterflies. It's also a good time to spot flowers, so don't forget to look down as well as up.

Two stone-curlew chicks (not the ones behind the visitor centre thoguh)