The local daytime temperature dropped from 23C on the 31st of March to 12C on the 1st of April, prefacing a prolonged period of cold weather from the 5th which lasted throughout the month and into May, often with single figure daytime temperatures and overnight frosts so severe that they caused my garden ponds to freeze over on a couple of occasions at the start of the month (all the frogspawn left in the main pond died). Bird migration slowed dramatically, although I did manage to find my first yellow wagtail of the year just north of Ashwell, on the Eyeworth Road, on the 3rd. Reed buntings seem to be faring quite badly in my region, with none seen within two miles of my house since 2019, and a male bird seen alongside the yellow wagtail was my first in Hertfordshire for the year, despite visits to the reedbeds of Amwell and Tyttenhanger. Golden plovers stayed in the Royston area until well into April, with flocks of about 120 flying around over Greys Farm and Park Farm on the 6th, 90 (now largely summer-plumaged) birds at Greys Farm on the 13th and up to 20 birds still at Greys Farm on the 19th. For the first time I failed to record a willow warbler on my local patch (within two miles of my house) in April, although birds were seen in the villages of Reed and Therfield (see below). Only two swallows (at Hatchpen Farm on the 17th) were seen during the month and I recorded no house martins, swifts or lesser whitethroats locally either.
Goldcrest, Therfield Heath, 20 April
Finding passage migrants on my 'local patch' also proved to be a struggle for me this year. I did eventually see three wheatears in a well-watched ploughed field at Greys Farm, just off The Heath, on the 8th. Up to eight were reported there in the following days, although when I looked on the 12th I again could only see three (two males and a female), with two present on both the 19th and the 26th. I have found ring ouzels on my local patch for the last six years, but there was no sign of any this April, although Andy Symes found an elusive individual off Coombe Road (Kelshall) on the 12th. I decided to visit Weston (near Baldock), where I caught up with a well-watched individual, as well as a young male redstart, on the 8th.
Two Male Wheatears, Greys Farm, 8 April
Male Ring Ouzel, Weston, 8 April
I recorded common snipe, white wagtails and a pair of shelduck, as well as lots of little ringed plovers, on two further visits to Stanborough gravel pit. After a couple of weeks' absence two flocks of Fieldfares (25 + 58) were seen during a walk to Hatchpen Farm on the 7th. My guess is that these were stopping off on migration from further south, rather than local wintering birds.
I recorded 48 bird species (44 seen) on a long walk through the villages on the 12th. The wintering mute swan had finally left Mardleybury Lake, but a little grebe was seen - my first local sighting of the year for this species, which has bred or attempted to breed here for each of the last three summers. Nothing new was seen on the walk, with a flock of 115 fieldfares in Therfield, displaying lapwings in two places and a single raven over Greys Farm being minor highlights. Whitethroats arrived back in the final week of April, with five recorded on a walk part way up the Icknield Way from Royston Hospital, but by the end of the month I had only recorded these and two other warbler species (chiffchaff and blackcap) locally. However, on the final day of the month I did hear a nightingale singing intermittently at Wisbridge Farm (Reed), my first since the 'Tesco filling station' bird.
Willowchaffs
When people talk about 'willowchaffs' they are usually referring to a sighting of one of the two small, brown phylloscopus warblers willow warbler and chiffchaff, which are hard to separate in the field when they are not singing. However, I have come up with a different definition - a willow warbler that incorporates chiffchaff phrases into its song. I first came across one of these birds in Reed village in 2020 and sound recorded it. This April I came across two more birds, one at Oughtonhead (Hitchin) and the other south of Therfield village, which did the same thing. Their willow warbler song is very clear and unmistakeable, whilst the chiffchaff phrases are, in varying degrees, more hesitant. My explanation of this strange behaviour is that, as breeding chiffchaffs are becoming more common in the Hertfordshire area whilst breeding willow warblers are becoming increasingly rare, the young local willow warblers in the nest are picking up both the songs of their fathers and of the surrounding singing chiffchaffs. I am not the only person to have recorded this phenomenon. Other explanations would be welcomed!
'Willowchaff', Therfield, 22 April
Insects
Insects were thin on the ground in the cold weather, but I did enjoy the antics of the hairy-footed flower bees at Hatchpen Farm, where they nest in a bank. The males buzz around outside the holes that the bees make in the bank, whilst the females fly directly into the holes with (presumably) pollen. These bees are only on the wing between March and May, so they disappear at least three months before ivy bees (which also dig holes) emerge in the early autumn!
Female Hairy-footed Flower Bee, Hatchpen Farm, 12 April
Male Hairy-footed Flower Bee, Hatchpen Farm, 29 March
I saw and photographed a few common species of hoverfly (Eupeodes luniger, Syrphus ribesii, Eristalis pertinax and an unidentified, tiny fly which annoyingly always perches with its wings closed over its abdomen) in the garden and the local woodland. Perhaps more interestingly, I noticed several individuals of what I believe is a nomad bee (possibly Gooden's nomad bee) in the local wood. The females of this species parasitise other bees (Andrena spp.). I did find a possible Andrena individual nearby, but was unable to identify it.
(Gooden's?) Nomad Bee, Green Walk Plantation, Royston
I only saw five species of butterfly on my local patch in the whole of April - a very disappointing total, but hardly surprising given the cold conditions. The temperature barely rose above 15C, and then only for a few hours during the middle of the day when the sun was out. Orange tips and green-veined whites joined the over-wintering brimstones, peacocks and small tortoiseshells on the wing, with at least 30 green-veined whites and ten male orange tips active along the Icknield Way on the 30th. Things can only improve in May - can't they?
Other Flora and Fauna
Pasque flowers put on a good display again on Church Hill, despite the very dry and cold weather, as did cowslips on various parts of The Heath and bluebells in the woodland along the ridge between Barkway and Sandon. Hares were very active, with eight being seen in the ploughed field at Greys Farm on the 19th.
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