Hello, and welcome to this weeks' blog. The migrant birds have continued to roll in, and I was greeted by two singing whitethroats when I arrived this morning. One was reported yesterday, along with a singing reed warbler (though this is unconfirmed). Yesterday (10 April) also brought a report of a wheatear but no further sign of the single cuckoo and hobby reported last week. The reedbeds are filling up with singing sedge warblers, which are joining plenty of Cetti's warblers. The latter don't migrate so they become especially vocal as soon as the weather warms up, and in the willows dotted throughout the reedbeds and along the fringes you will struggle not to hear a chiffchaff! Our avocet numbers reached an all-time high of fourteen this morning (11 April) on the Washland; look out too for other waders including redshank (7 recorded on 3 April), oystercatcher (4 on 9 April), the odd curlew and lapwing too (5 on 9 April). Garganey have been lurking at the back of the Washland, or on the mini-wash north of East Wood, for several days now and we have had up to six here five drakes, one duck) so these are worth looking for. They may be a long walk away so try looking either from further along the footpath, where it curves round and brings you closer to the western end of the Wash, or using a telescope if you have one from the viewpoint. You should see a variety of ducks there too, especially shoveler, shelduck, teal and gadwall, as well as up to five great white egrets and a couple of little egrets. The Washland has also become an excellent spot to see sand martin and swallow, in mixed swooping flocks as they catch insects over the water. We are still waiting for our first house martin but we can expect that in the next few days. Our great crested grebes have moved from the river into breeding mode and are looking splendid in their summer finery, and are now paired up and beginning to settle on the quiet pools across the reserve. Here's a lovely photo of a pair sent in to us earlier this week: Photo credit: A pair of great crested grebes, photo taken by Sharon Rayner on 4 April 2021.The white stork (we aren't sure if it is an escapee) has been seen regularly with a fifteen-minute flying session over Joist Fen this morning, though it is more likely to be encountered by looking north from the riverbank footpath onto farmed fields, where it spends most of its time. Another giant bird that visited us this past week was the well-documented white-tailed sea eagle- a juvenile from the Isle of Wight reintroduction programme (courtesy of the Roy Dennis foundation) which arrived at approximately 15:00 on 7 April and stayed until 10:00 the next day, before moving onto Hunstanton on the north Norfolk coast by lunchtime. A few lucky visitors got to see it and even sent in some photographs (see our Facebook feed for these). Marsh harriers are displaying all the time over the reedbeds- in fact it would be hard to visit the reserve at the moment without seeing one- listen for the males' 'yelping' calls from within the reedbeds, or for males displaying acrobatically above them, or perhaps carrying sticks, intended as nesting material. Females will sometimes be in the air with them, or are often sat in a willow or blackthorn bush watching one or more males. It is the males' job to impress her, and her job to judge which male has the best suggestions regarding nest sites and the best aerial displays! Below is a photograph kindly shared with us of a pair flying together. Other birds of prey include single sightings today again of our male hen harrier over Joist Fen and a peregrine from New Fen- the best chance you have of seeing either of these will be to wait a while at the viewpoints and keen an eye out over the tops of the reedbeds. If you visit in the morning you are likely to hear one or two of the several booming bitterns on the reserve- one of our volunteers had four this morning. From the results of the weekly bittern surveys it would seem that we have between six and eight territories (and boomers) on site this year. Our bearded tits are very quiet at the moment, as is to be expected at this time of year when they settle down to breed. Visitors are still seeing the odd common crane in flight and one or two are reported most days. Photo credit: A marsh harrier pair by Sharon Rayner, taken on 4 April 2021.Where insects are concerned, things are happening at a slower, quieter pace but 7 April saw our first orange-tip and green-veined white butterflies of 2021- on a particularly warm and sunny day. These two species are quite closely related and follow similar habits- they will both lay their eggs on Dame's-violet and garlic mustard, and in this respect the green-veined white is much less like the small and large whites. They also have a dainty, quick flight pattern, like the orange-tip, and the females of both species can look very similar. We are now on five butterfly species, thanks to comma, brimstone and peacock being seen earlier in the year.As we move through spring it is a very interesting time for a visit to the reserve- some winter visitors such as siskin and brambling are still here, in fact a singing brambling was heard at the Visitor Centre on 9 April and again this morning. In the past week, redwing and whooper swan have been spotted in small numbers across the reserve, but these are now naturally much harder to see.I hope you have enjoyed this weeks' blog. Here is a reminder of our opening hours and facilities: - Outdoor Welcome Point and toilets (including an accessible one) open daily, 09:00 to 17:00 during the week and 09:00 to 16:00 at weekends- Takeaway refreshments available from the Welcome Point daily, 09:00 to 17:00 during the week and 09:00 to 16:00 at weekends- Most trails (aside from a temporary path closure), all viewpoints and the car park open daily from dawn until dusk- Mere Hide remains closed, for now.With best wishes for a happy weeks' birding,Heidi Jones (Visitor Experience Officer, RSPB Lakenheath Fen).