April 2013 Sightings

[Jack Harrison]

APRIL

There is often a gentle competition each month to make the first sighting report. Well I can’t report a sighting, but I do make a prediction.

The emergence dates of butterflies are affected by many factors: Photoperiod (Day length): Total sunshine during spring months: Temperature: Rainfall.

Some species are very predictable: Purple Emperor can be forecast almost to the day (photoperiod response). In general, in recent decades, emergence dates have got earlier, probably due to increased temperatures and sunshine in the spring (but not in 2013!).

But one species doesn’t seem to have been affected as much as others: Orange Tip. When I was a youngster in the south of England in the late 1940s, I would expect to see Orange Tips from about mid-April. Today, the season has hardly changed.

I happened to be looking up Sea Turtles and the fact that egg-laying is dependent on the phase of the moon (thus on tides). I witnessed this phenomenon when working in Oman (Masirah) many years ago. Now I have looked back on my records for Orange Tip and found the peak emergence each April is round about the date of the second spring tide of the month, ie a day or two after New or Full Moon. So for April 2013, I would anticipate the peak Orange Tip emergence to be around 26th April (second April spring tide approx 26th. after Full Moon on 25th)

I offer no explanations and it will need a statistician to analyse my data to see if there really is a correlation. I have already asked our resident mathematician Guy Padfield (via a PM) to look into this, but as you will know, he has been away so might not have had too much spare time to work on the data.

Jack

[Padfield]

Hi Jack. It's a simple enough hypothesis to test but I'm afraid I haven't had a chance to do the number-crunching yet. On first sight, it looks completely compatible with the data you sent but the probabilities have to be worked out to ensure this is statistically significant and not just chance.

Easter, of course, is set as the first Sunday after the first full moon after the equinox. A lot of people want to change this to a fixed date, but I propose we change it to the first Sunday after the second new or full moon in April. This is equally easy to calculate and should result in a delightful profusion of orange tips on the feast day.

Guy

[Susie]

Indeed. Perhaps we could start a new trend by dipping the tops of standard easter eggs into orange chocolate so they have their very own orange tips.

Tangentally, mothers (human) are more likely to go into labour at a full moon due to the pull on the waters so it wouldnt surprise me at all if this caused more eggs to hatch too.

[Jack Harrison]

Susie

Tangentally, mothers (human) are more likely to go into labour at a full moon due to the pull on the waters so it wouldnt surprise me at all if this caused more eggs to hatch too

Yes but in the case of Orange Tips in April, it would be the chrysalises hatching, not eggs.

Come to think of it, Orange Tip eggs MIGHT hatch two weeks later at the next spring tide. That's about the right interval from adult emergence to egg emergence.

Jack

[David M]

This is one year where any reported sighting WOULD have been an April fool!

3c, cloudy and windy here in Swansea. Even the seagulls look fed up!

[sahikmet]

Not an April fools joke, but one from Madeira, just back. Madeiran speckled wood?
Cheers
Sezar

[Padfield]

I fear that is its rival, the speckled wood. The outer margin of the forewing is convex in xiphia (Madeiran speckled wood) and slightly concave in aegeria (speckled wood). Sorry!

Guy

[sahikmet]

Thanks, rather confusing. Sezar

[NickB]

No - it is not a late April Fool joke....
I DID see a Comma this afternoon, my first butterfly for nearly a month!

[NickB]

I fear that is its rival, the speckled wood. The outer margin of the forewing is convex in xiphia (Madeiran speckled wood) and slightly concave in aegeria (speckled wood). Sorry!
Guy

Yes - The specimen from sahikmet is the nominate form of P. aegeria aegeria (Collins p.319) which looks quite different from our own Speckled Wood P. a. tircis.

[Padfield]

Bright and blustery in East Anglia today - and cold!

On a quick lunchtime bike ride I found two small tortoiseshells braving the chill, though neither looked particularly happy about it.



Beds of nettles are pushing up all over the place so I was surprised not to see more, nor any peacocks or commas, but it was nice to see a butterfly, at least, on this visit to Suffolk.

Guy

[marmari]

At Walters Copse,Newtown,IOW today at last,two commas contesting and enjoying a very sunny and warm spot.No other sightings.

[badgerbob]

It was a very cool breeze blowing today across the scarp face at High and Over. One Wall Brown larva found easily, but this was the only one found. Another larva found is believed to be an early instar Oak Eggar. A superb Red Kite also flew along the bottom of the scarp giving great top views of this bird which is seen only occasionally in these parts. Sunny nearly all day but temperatures struggling to only 6 degrees and feeling colder than that in the wind.

[David M]

Thank God there are butterflies still alive!!

Two or three windy days to go but the weekend is looking relatively benign. We're only due highs of 9c but with light winds and plenty of sunshine I daresay that'll suffice for a bit of movement. With any luck I'll finally get conditions sufficiently pleasant to ascend Kilvey Hill behind my house!

[Neil Freeman]

Went for a walk around a couple of local spots this afternoon. There was an underlying cold wind but in some sheltered spots I could actually feel the warmth of the sun for the first time

One such spot on the sheltered side of a hedge gave me my first butterfly of the year, a rather tatty looking Small Tortoiseshell that I disturbed from basking on the path. I soon lost sight of it but that one brief sighting made my day

Neil F.

[Jack Harrison]

Finally from Mull.

Not my sighting - I am confined to my sick bed with some ridiculous lurgy - but wife proudly reported a Tortoiseshell in the garden.

Jack

[NickB]

Finally from Mull.
Not my sighting - I am confined to my sick bed with some ridiculous lurgy - but wife proudly reported a Tortoiseshell in the garden.
Jack

Get well soon Jack - I'm missing my daily dose of life in Tobermory....

[MikeOxon]

I am confined to my sick bed with some ridiculous lurgy

Get well soon, Jack - I'm sure that a few doses of 'medicine' from the local distillery will soon have you right again

Mike

[Jack Harrison]

And now a Peacock - and I'm still stuck indoors but improving slowly.

Jack

[David M]

Managed to get halfway up Kilvey Hill after work this afternoon and I DID see a butterly - a rather battered Small Tortoiseshell flying up towards the peak.