Monday, 3 July 2017

1976 (and other hot summers) …

How times have changed …


The prolonged spell of extremely hot weather in 1976, from mid June to the end of August, including fifteen consecutive days where a maximum temperature of 32°C or more was recorded somewhere in the UK, was one of the most protracted heatwaves within living memory. Below average rainfall was notable from May 1975 through to August 1976 resulting in one of the most significant droughts on record.

Apart from the unbearable temperature, the one thing I will always remember from the summer of 1976, in addition to sitting my final exams at school, was the abundance of Silver-washed Fritillary (Argynnis paphia) in Worth Forest, my local Sussex woodland. Pearl-bordered Fritillary (Boloria euphrosyne) and Small Pearl-bordered Fritillary (B. selene) were also abundant to the point where we took them for granted; after all they would always be there - or so we thought. A. paphia is fortunately still present in many Sussex woodlands but our smaller woodland fritillaries are sadly now absent from most of their former haunts. B. selene, which became extinct in Sussex in 2013, is now the subject of a reintroduction programme to its former stronghold.

A warning to value what we have and not take things for granted.

More at:

Blencowe, M. and Hulme, N. (2017). The Butterflies of Sussex. Newbury, Berkshire: Pisces Publications on behalf of Butterfly Conservation (Sussex Branch), pp. 136-145, 146-151 and 152-157.
Pratt, C. R. (2011). A Complete History of the Butterflies and Moths of Sussex. Peacehaven, East Sussex: Colin R. Pratt, 2, pp. 257-261, 261-265 and 275-278.

Friday, 30 June 2017

Cnoc Salltraim ...

Cuckoo (Cuculus canorus)




C. canorus is a familiar herald of spring and a species that is thinly distributed over a wide breeding range throughout most of Britain, Europe and the Palearctic. It is a fairly common but rapidly declining summer visitor to Sussex, where the males commence singing soon after their arrival; typically in early April. Recent satellite tracking technology has shown that the males usually leave the UK to their wintering area south of the Sahara only a few weeks after first arriving here in the spring.

C. canorus has a well-known breeding strategy as a brood parasite, laying its eggs in the nests of other birds; typically those of the Dunnock (Prunella modularis), Meadow Pipit (Anthus pratensis), Pied Wagtail (Motacilla alba) and Reed Warbler (Acrocephalus scirpaceus) in the UK. The female, who will specialise in one particular host species, will only ever lay one type of egg and will always target her egg-laying appropriately. The genes for egg pattern and colour are thought to be carried on the female chromosome, so they are passed down from mother to daughter regardless of who the female mates with. This means that a Cuckoo targeting a Reed Warbler always produces eggs with a Reed Warbler pattern and she knows which nests to target thanks to the process of imprinting. As a young chick, she will have learned to recognise the song and appearance of her foster mother; and as a returning adult she will seek out the nests of females that match this mental image and lay her eggs accordingly.

The above images of a female were recently taken on North Uist in the Outer Hebrides.

References:

Yates, B. (2014). Common Cuckoo. The Birds of Sussex. Thetford: British Trust for Ornithology (BTO) Books on behalf of the Sussex Ornithological Society, pp. 360-361.
Whitcomb, P. (1996). Cuckoo. Birds of Sussex. Sussex Ornithological Society, pp. 358-359.


Saturday, 24 June 2017

In context …

Purple Emperor (Apatura iris)


A. iris is best seen through the early morning and again during the late afternoon, when the males come down to the ground, on hot humid days, to take in nutrients from damp earth and animal droppings. They are also partial to human sweat - a key component of Emperor watching - and readily land on observers. Despite this ‘grounding’ behaviour, both males and females spend much of their time resting or feeding high within their arboreal home and out of sight.

The above image shows a male feeding on honeydew high in the oak canopy.

More at:

Thursday, 22 June 2017

Cause and effect …

Purple Emperor (Apatura iris)








2017 is turning out to be a very early season for many species of butterfly. My first sighting of iris this year came on Saturday, 17th June when I recorded three males and a female in Chiddingfold Forest. On the same day, a friend recorded four males in a nearby area of the same forestry complex. Our joint feelings were that they’d been out for a maximum of 48 hours. The earliest I’ve ever recorded iris is a sighting of a solitary individual on 12th June 2015. However, for whatever reason(s), that same year I didn’t see another in my local woodlands until 4th July. A highly unusual and freak encounter or are things changing?

One must always be cautious when claiming ‘cause and effect’ with regards to the timing of a butterfly’s flight season. One thing that is evident is that the vast majority of our butterfly species have demonstrated a clear and unequivocal response to climate warming, with their average first appearance dates and abundance peaks now being significantly earlier than they were (Blencowe and Hulme, 2017). The flight periods of most of our species, measured in terms of first annual appearance, the first appearance of subsequent broods (in polyvoltine species), and abundance peaks, have moved forward by between one and three weeks in 20 years, with an average based on 40 species being about 13 days. Interestingly, a few species registered very little response to a warming climate; these included Meadow Brown, Gatekeeper, Silver-washed Fritillary and Brown Hairstreak (Blencowe and Hulme, 2017).

These days iris usually flies from late June to early August, with most adults emerging over a three week period; the average flight season recorded between 2010 and 2014 in Sussex was 28th June to 9th August. However, during this five-year period, two late years (by modern standards) were recorded. The typical first appearance date during the 21st century is now a little earlier, usually falling between the 20th and 25th June. During the later decades of the last century iris usually emerged in early July, so the flight period has shifted forward significantly, by at least two weeks (Blencowe and Hulme, 2017).

The above images show (i) a male from 17th June 2017, (ii) a male from 23rd June 2017, (iii) a female from 19th June 2017, and (iv, v, vi and vii) four images of two females from 21st June 2017.

More at:

Blencowe, M. and Hulme, N. (2017). The Butterflies of Sussex. Newbury, Berkshire: Pisces Publications on behalf of Butterfly Conservation (Sussex Branch), pp. 27, 170-179.

Sunday, 18 June 2017

Loch Fada na Gearrachun …

Short-eared Owl (Asio flammeus)



A. flammeus is a scarce winter visitor and passage migrant to my home county of Sussex. Wintering birds are found mainly on the coastal plain, especially around Chichester and Pagham Harbours, on the Pevensey Levels and at Rye Harbour. They also occur in smaller numbers on the Downs and in the river valleys of the Adur, Arun and Ouse. Autumn migrants are generally first seen in Sussex in late August or early September where they typically continue their journeys south to more southerly wintering grounds. If weather conditions are favourable and prey numbers are high, birds arriving from late September onwards are likely to remain in Sussex for an extended period and may settle down and winter in suitable areas.

An estimate of the Scottish population suggested 780 to 2,700 breeding pairs (1,000 - 3,500 pairs for the UK) in the late 90’s; although this is thought to be one the most unreliable estimates for any raptor or owl species. A more recent estimate (2013) for Britain is 610 to 2,140 pairs. Some experts consider the lower end of these ranges to be the more likely and are concerned that the species may have shown marked declines during the past two decades.

The above images from North Uist in the Outer Hebrides.

References:

Green, D. (2014). Short-eared Owl. The Birds of Sussex. Thetford: British Trust for Ornithology (BTO) Books on behalf of the Sussex Ornithological Society, pp. 369-370.
Patton, S.J. (1996). Short-eared Owl. Birds of Sussex. Sussex Ornithological Society, pp. 366-367.

Wednesday, 14 June 2017

Early bird ...

North Uist, Outer Hebrides

The rewards of an early morning approach ...




The first two images taken before 6am ….

More at: