The hot weather continued into the start of May, with temperatures reaching around 27C, before declining dramatically as north-easterly winds set in from the 3rd. By the 4th the temperature in mid-afternoon was just 13C with a significant wind chill factor making it feel even colder, and I had gone from a light polo shirt to three layers, with a fleecy jacket on top. Whilst the weather was still hot on the 2nd I visited Church Hill and was encouraged to see at least ten (presumably) male Brown Argus butterflies flying over the low-cut grassy slopes, after this species did so badly in 2024. The cutting of the grass here in late summer last year should benefit this and other 'blue' species. Also seen were two Small Heath butterflies and small numbers of Peacock, Brimstone, Red Admiral, Comma, Orange Tip and Green-veined White butterflies.
Small Heath, Church Hill, 2 May
The warm weather soon returned, with prolonged sunshine during the middle of the month. Back on Church Hill on the 7th I couldn't find any Brown Argus butterflies (they only live in the adult stage for a few days), although a single Common Blue butterfly was seen at the bottom of the hill, a very early Broad-bodied Chaser dragonfly was seen nearby and a Mother Shipton moth (also seen on the 2nd) was photographed. This attractive, day-flying moth has a beaky 'face' marking on each wing, presumably giving it its name: see if you can make it out on the image (below). I was pleased to see that two male Spotted Flycatchers were 'singing' (a few high-pitched, squeaky notes) in Fox Covert on either side of the Therfield Road. This is a very early return for a species that can turn up as late as the beginning of June, but there had already been several reports of this species before 'my' birds were seen.
Mother Shipton Moth, Church Hill, 7 May
Singing Spotted Flycatcher, Therfield Heath, 7 May
Ox-eye Daisies, generally a flower of early June, were already flowering when I walked up onto The Heath on the 13th. I noticed that a fly was apparently sitting on one flower head. Closer inspection revealed that it had been captured by a predatory Crab Spider (stealth killers - they don't make webs), which was smaller than the fly (image below). On The Heath, three male Adonis Blues were flying on the Old Rifle Range, and looked to have been on the wing for at least a couple of days. This is fairly early for Adonis Blues, and was no doubt due to the fine, sunny weather in April and May.
Male Adonis Blue, Therfield Heath (Old Rifle Range), 13 May
Crab Spider with Fly Victim, Royston, 13 May
In 2023 and 2024, Chalkhill Blue butterflies did not emerge on Church Hill, although a few were seen flying there in the late summer of 2024. After only a few Adonis Blues were seen here in the spring of last year, and no second generation was seen, I assumed that the latter species had been lost to the poor weather at this site. However, when I checked the south side of Church Hill on a sunny afternoon on the 16th I was surprised to see several male Adonis Blues and a single female flying. As previously mentioned, Church Hill had been mown in the late summer of 2024 and was now covered in Horseshoe Vetch. Was there an unnoticed, very small second generation of Adonis Blues in 2024, or could the adults possibly have started life as eggs laid by last year's first generation? Another possibility is that they were re-introduced by whoever originally introduced them to The Heath. I guess that I'll never know. Present with the Adonis Blues were several Common Blues (all males) and Brown Argus butterflies, whilst in Fox Covert another Broad-bodied Chaser dragonfly was seen. A similar mixture of butterfly species was seen when I returned to Church Hill on the 21st, with slightly fewer Adonis Blues and Brown Argus, but even more male Common Blues.
Female Adonis Blue, Church Hill, 16 May
Roosting Brown Argus, Church Hill, 16 May
Male Common Blue, Church Hill, 16 May
Broad-bodied Chaser Dragonfly, Fox Covert, 16 May
Wasp Beetle, Royston, 19 May
Other sites visited in Hertfordshire during May included Wilstone Reservoir (Shelduck, Hobby, Swift, Common Sandpiper, Dunlin and Little Ringed Plover seen on the 8th) and Amwell, where I saw my first Red-eyed Damselflies and Banded Demoiselles of the year on the 12th.
Common Sandpiper, Wilstone Reservoir, 8 May
Four-spotted Chaser, Amwell, 12 May
Red-eyed Damselfly, Amwell, 12 May
The weather became more changeable towards the end of the month, although still with some warm, sunny days. Another visit to Amwell on the 23rd provided me with sightings of Cuckoo, Cetti's Warbler and a very early Green-eyed (Norfolk) Hawker dragonfly. A Great Crested Grebe caught and ate a large Crayfish whilst I was watching (image). The 26th saw me at Hillbrow (Letchworth), looking for Small Blue butterflies. I did eventually find half a dozen on a very windy day, but there was little else to see until a male Orange Tip butterfly fluttered by and conveniently stopped for me to photograph it.
Great Crested Grebe with Crayfish, Amwell, 23 May
Male Orange Tip Butterfly, Letchworth, 26 May
Small Blue, Letchworth, 26 May
A large flock of Ringed Plovers (12-15 individuals) arrived at Wilstone Reservoir in late May, staying for a few days. These birds, which looked slightly different to the birds that I see on the Norfolk coast, were likely passage migrants, heading to breeding sites in Northern Europe. I went to see them on the 28th. A Little Ringed Plover (resident?) and two Dunlins were also seen. Whilst I was in the area I took a walk along the Grand Union Canal from Wilstone village. A single, female White-legged Damselfly was seen on the bank of the canal, and I also had a bit of fun trying to photograph the very mobile Banded Demoiselle dragonflies on another windy day.
Ringed Plover, Wilstone Reservoir, 28 May
Male Banded Demoiselle, Grand Union Canal near Wilstone, 28 May
Locally, I found what I believe is an 'instar' Speckled Bush Cricket (only about 5mm long) on a walk along the Icknield Way east of Royston on the 27th and three Bee Orchids in a hollow on Church Hill on the 29th. When I came back with my macro lens to photograph the most impressive of the orchids on the 31st I was lucky to see a very early Marbled White butterfly, the first to be reported in the Herts. and Middlesex region and the first that I have ever seen in May. No Adonis Blues were seen on either visit, although they were reported by others visiting The Heath at the end of May and early June.
Immature Speckled Bush Cricket (?), Royston, 27 May
Bee Orchid, Therfield Heath, 31 May
'Record Shot' of Marbled White, 31 May
In the garden, recently fledged birds started to appear towards the end of the month including, surprisingly, juvenile Greenfinches. Blue Tits, Great Tits and Blackbirds also brought their young into the garden, whilst frenetic Starling activity and noise suggested that their young would soon be fledging.
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