With migration in full swing, July often brings an unexpected visitor or two to the Suffolk coast, but nothing could really prepare us for the events that have unfolded this week.
The excitement began on Monday morning when our Senior Site Manager, Adam Rowlands, called on the reserve radios to say that he thought he had a large tortoiseshell butterfly in his garden. This was potentially a first reserve record of this rare migrant, which used to breed in the UK, so a handful of us rushed across to take a closer look. Sure enough, sitting on the bungalow guttering was an unusual tortoiseshell butterfly. It was slightly larger and paler than the familiar small tortoiseshell and had a slightly different upperwing pattern. After consulting a field guide and taking a few photos we alerted other colleagues to have a closer look.
The butterfly promptly flew to the top of the bungalow roof to soak up the sun, before eventually providing excellent views as it fed on nectar from a buddleia bush. There had clearly been a large arrival of migrant butterflies as the bush was full of red admirals and large whites, with a few painted ladies, as well as newly emerged peacocks, a few graylings and commas and even a purple hairstreak. Unfortunately, it was difficult to arrange wider access that day.
Large tortoiseshell would have been a new species for most of us, but things were about to get even more exciting. During the evening questions were asked on Twitter (@RSPBMinsmere) about whether we had ruled out yellow-legged tortoiseshell. After some internet research I discovered that this butterfly, which had only once been seen in the UK (in the 1950s) had been seen in large numbers in Holland over the last couple of days - for the time ever. The two species are very similar, apart form leg colour, so easily confused - especially when you're not even considering one of them! My photos didn't show the legs, but others did, and we were able to confirm the identification as yellow-legged tortoiseshell, also known as scarce tortoiseshell. They usually occur in eastern Europe and are very rare in the west.
Photos by Robin Harvey. A short video clip by David Fairhurst clearly shows the yellowish legs - https://vimeo.com/100827316
Luckily the butterfly was still present on Tuesday, so we arranged for guided access to the garden to watch it. A few visitors were lucky enough to see this amazing butterfly before it suddenly vanished at about 11 am and was sadly not relocated.
There was some consolation for those unlucky enough to miss this butterfly, as a rare bird was located on the Scrape yesterday morning - a collared pratincole. This was the first time this wader had been seen at Minsmere, or anywhere else in Suffolk, since 1996, so it attracted a lot of attention. Although it could be difficult to spot at times, it also gave some great views as it flew over the Scrape in pursuit of insects, or simply jumped to catch flies. Collared pratincoles breed in Spain, locally elsewhere around the Mediterranean, then from Greece eastwards through central Asia and only a handful visit the UK each year. The bird is still on the Scrape as I type.
There's a superb variety of waders on the Scrape at the moment as birds pass through on migration. The most numerous species are avocets (upto 200) and black-tailed godwits (upto 150), but there are also several spotted redshanks, ruffs, green and common sandpipers, greenshanks, dunlins and little ringed plovers, as well as the odd wood sandpiper and whimbrel. There's also an increasing number of little gulls (36 today) and a few common, little and Sandwich terns, while a spoonbill was spotted on Monday too. This week we are planning to open the seasonal path to view the North Levels pools, which are also great places to spot waders and herons and give a different view of Minsmere's reedbeds.
The tortoiseshell isn't the only rare insect seen at Minsmere this week either. Two of our most distinctive day-flying moths have been seen on the buddleias at the visitor centre too - the hummingbird hawkmoth and the relatively similar broad-bordered bee-hawkmoth. The latter can regularly be seen patrolling from flower to flower, with it's bee-like colouration.
Broad-bordered bee-hawkmoth by Ian Barthorpe
With so many eyes looking at buddleias it's perhaps not a surprise that other insects have been seen too, including a varied mix of hoverflies and bees. And today we've found another rare butterfly, at least as far as Minsmere is concerned. The silver-washed fritillary is one of our largest butterflies and has slowly been colonising parts of East Anglia in recent years. This is at least the third consecutive year that one has been seen at Minsmere suggesting that they might be breeding locally. It too, has favoured the area in front of the visitor centre, though it has been quite mobile.
With so much excitement our bitterns, bearded tits and marsh harriers may be feeling a bit left out, but they're continuing to show well too, and a few hobbies remain over the reedbed. And, of course, many of our commoner plants, birds and insects can still easily be spotted as you wander around the reserve.