Steady Progress! Skin Changing

Emperor larvae are making steady progress this early spring, in the fine weather. A few are already starting to change skins, to the 4th instar (L4). 

Most are at this stage (late-L3, feeding on leaf undersides from a silk pad on the stem) - 

Or this -

This one's interesting. He's 5m up on a sallow, trackable only through binoculars. His silk pad is next to a slow-developing leaf bud, so he's feeding on a loosening bud 10cm up-stem. You can see his silk trail running up to his feeding bud - 

It's far too early to speculate on when the flight season will begin, but some of the midsummer species are well advanced (notably High Brown Fritillary, which should be out in late May this year down south...)

High Winter Survival Rate

Delighted to be able to report the lowest level of (assumed) titmouse predation in sixteen winters of close study in Savernake Forest. We only lost one larva to definite bird predation, though another has just been listed as Missing in Action, after having woken up from hibernation...

Crucially, we didn't see a single tit flock in the forest all winter, and recorded only the odd individual Blue, Great and Marsh tits. There's a strong correlation between tit populations going down and Emperor populations going up!

However, three other larvae either desiccated in late winter or had their innards sucked by predatory invertebrates (e.g. shield bugs or Tree Damsel Bug).

Yesterday, most surviving larvae were poised next to buds, waiting for the bud to swell and loosen, so that they can start feeding. But one early bird, on a non-flowering branch that sprang into leaf early, has been feeding for over a week, has grown noticeably and will start to change skin to the 4th instar next week. Here he is -

Elsewhere, two larvae have just started to feed in Gloucestershire.

Emperor larvae are currently bang on time. This time last year they were romping ahead and were threatening to be on the wing at the end of May! There's no sign of that happening, yet.

Watch this space, this Emperor season is getting interesting...

Greening Up!

Emperor larvae are starting to green up: changing their dull winter coats for the green of the spring, like this (yesterday, in Savernake) -

We checked 11 hibernating larvae in Savernake yesterday. Incredibly, only one out of the original sample of 12 has been lost to bird predation this winter (fingers crossed...). In most winters there, bird predation (titmice mainly) is in the 50-75% range! (Sample size is a problem, obviously).  

I've hardly seen any titmice in Savernake all winter...  When tits are down, Emperors go up...

However, we have lost two larvae in Savernake since mid-Feb, to shrivelling. Like this -

I suspect that this one has had its innards sucked out by a predatory bug, but it may be a virus or diet deficiency - very hard to tell. The second shrivelled one was 5m up, found by Dangle Leaf and spotted & monitored through binoculars - so never seen close up. 

Shieldbugs and the Tree Damsel Bug seem to be appearing earlier and earlier in modern mild winters (though there's no baseline here, no one's been studying them on sallows...). 

In captivity, quite a few larvae simply shrivel up in late winter. We don't know why (?? inadequately fed the previous autumn, ?? run out of fuel in the tank).

Soon, very soon, larvae which have been wintering in forks and scars will move up to swelling buds. A run of cold nights has prevented this happening already.

Also, back in the Cotswolds, in the wooded valley near Daneway Banks, we found a new larva - only he's missing half of his left 'horn', presumably bitten off by some invertebrate predator. I followed one which had its right horn missing during the 2017-18 winter, named 'Stumpy': it got through the winter, fed nicely in April, changed to L4 but promptly died. So, finger's crossed for this one (also called Stumpy) -

At this range, larvae are likely to start feeding in early April.

  

Mid-Feb News

Yet more good news from Savernake Forest. We have still lost only a single hibernating larva to (probable bird) predation all winter. I checked the surviving 11 yesterday: all present and correct, unmoved. This is by far the best mid-Feb survival rate there in 16 years... Finger's crossed...

I am still hardly recording any titmice there (and then mostly in the Leigh Hill area, close to cottage gardens, where they're being fed...  Maybe they're all wintering in gardens in Marlborough!).

The weather's set to change this week, with much milder conditions setting in (after six weeks in which temperatures have stayed within the normal mid-winter range band). 

This means that many larvae will wake up. Those not settled by buds are likely to migrate up to buds, and settle there, in waiting (and the buds haven't moved yet). They are vulnerable when they move...

Here's one in silhouette from yesterday. This one's likely to stay put -

But this one, in a sunny spot on a branch scar, is likely to migrate half a metre or so up to a leaf bud -

That's the good news. The bad news is that I've lost four of the six larvae I've been following locally, in the upper Frome valley west of Cirencester (near Daneway Banks on the butterflying map). All four were on buds. 

The two hibernating a metre or more from the buds are still extant (one in a branch fork, one on a twig scar). I suspect a rogue resident bird (not a Great Tit, none there) or, more likely, a regular visiting flock of Long-tailed Tits. These larvae will be vulnerable when they move up to leaf buds, so I'm going to put some chicken netting around them... 

More Good News!

Delighted to be able to report that so far this winter (3rd Feb) we have only lost one out of 12 larvae to (bird) predation in Savernake.

That's the lowest predation mortality figure on record there, from a double-figure sample, since monitoring began in the 2009-10 winter. 

We also lost one to flail cutting...

Here's The Gallops No 1 in repose in a branch scar yesterday. This is a sensible place to hibernate -

In the woods to the south of Savernake, 8 out of 11 larvae survived January. That's still good...

However, losses tend to be highest during February, so don't get over-excited yet...

Titmouse numbers, especially of Great Tit (PE Enemy No 1), remain Low in the southern woods.  There are hardly any tit flocks in the woods (apart from of Long-taileds, which seem to have had a good breeding season last spring). But Great Tit males are just setting up territories in the woods now...

Fingers crossed, we could be on for a good or very good PE season this year, though much depends on the next six weeks and on weather during the pupation & pupal periods in late May / early June...

A lot of storm damaged old sallows, like this - 

 

 

Thank God We've Got Through January!

It's good to get rid of the year's worst month first (with apols to those who were born in January). For the record, weather-wise, Jan 2025 rather kept within its traditional parameters, with light frosts on most nights. It was, of course, horribly wet and ended with a vicious named storm (Storm Eowyn). 

Crucially, low night temperatures have slowed things down, which needed doing... and Big Garden Birdwatch suggests low numbers of Great Tits (PE enemy No 1).

Here are Isaiah, Ezekiel and Jeremiah, photoed yesterday -

February, though welcome, is the main danger month for tit predation on hibernating larvae. Watch this space...

 

3rd Degree Burns Poetry

Inspired by Burns Day, our Scots Poet-in-Residence Fiona Barclay, has risen to the following:-

The Emperor's Lament

Och, fair Emperor, sae grand, sae braw,

W' wings o' velvet rich and raw,

Ye reign o'er England's leafy law

But ne'er in Scotland's cauld, dreich snaw.

Frae oakwoods deep, ye tak' yer flight

A shimmerin' jewel in summer's light.

But here, nae sun tae warm yer wings,

Just wind that howls an' rain that stings.

Oor heathered hills, oor rugged glens,

Might charm the souls o' mortal men,

But tae a butterfly sae fine, sae rare,

They're nae but bleak an' cauld despair.  

Ah, tae see yer purple glory shine

Aboot the Rowan or Scots Pine!

Yet Scotland's skies are dour and grey,

Chasin' monarchs like yersel' away.

Sae here we bide, wi' midges rife,

And mourn the Emperor's absent life. 

For though oor land is wild an' free,

It's no a realm for likes o' thee!

I'll spare you the other 34 verses...

The good news is that the first Marsh Fritillary larval web appeared in the Saturated Wastes of Gloucestershire yesterday, bang on time -