A slow start to spring

Despite the tantalizing period of exceptionally early spring warmth, it has been something of a slow start to the season. There have been some early nests, with young Robins, Song Thrushes and Blackbirds evident in many gardens across the county, but other individuals were held up by the returning cold conditions. Now, however, it feels as if the pace is quickening.

We have seen a succession of arrivals, as returning summer migrants have been quick to settle on favoured breeding territories and deliver song. The Chiffchaffs were the first of these to be noticed here, around the brecks, followed by Woodlark, Blackcap, Willow Warbler and, most recently, Whitethroat. Early Reed and Sedge Warblers appeared late-month, with numbers of these reed- and sedge-bed songsters now increasing. The hirundines (swallows and martins) were slow to return in numbers and my first sightings of these summer visitors were behind those of recent years.

We have also had a smattering of passage migrants, in particular a good arrival of Ring Ouzels. These striking thrushes resemble a large Blackbird but with beautiful sculptured plumage markings and, in adult males, a white crescent around the throat. We have also seen some less common visitors in the shape of at least two Hoopoes, continental breeders that have overshot their breeding grounds off the back of southerly winds. They won’t linger, however, and will soon reorientate to return south. One of the most fascinating aspects of the unfolding migration has been the return of the Cuckoos, fitted with satellite tags by the BTO. Regular updates on their progress continue to appear on the BTO website (www.bto.org/cuckoos). The five tagged last summer, were all captured in East Anglia and it will be interesting to see if they return to the same sites.

The pattern of activity seen in our birds has been mirrored in the county’s butterflies, with a good number of early reports of species that overwinter in the adult form, followed by several lean weeks in which few sightings were forthcoming. Other species are now being reported on the wing, including Orange Tip and Holly Blue, so it does feel as if the butterfly season is now properly underway. Other insects have been taking advantage of early season nectar, with good numbers of bumblebees foraging in my garden and quite a number of hoverflies as well. The changeable weather that we see at this time of the year does deliver something of a stop-start feel and while it can appear that spring is here to stay one morning, the next can suggest a return to winter. It is a great time of the year to be out and about though as each new sighting delivers a thrill.

First 'proper' spring butterfly on the wing

Like me, you have probably seen a few butterflies on the wing over recent weeks. These may well have included Peacock, Small Tortoiseshell, Comma and Brimstone, all of which overwinter as adults. Just possibly, you may have encountered a Red Admiral, a species which has recently demonstrated its ability to overwinter here as an adult, but which is likely to have struggled this particular year because of the severity of the weather.

Orange Tip, by MIke Toms

Our other butterflies overwinter at different stages of their life-cycle, with some spending the winter as caterpillars, others as eggs and some as pupae in a chrysalis. The Orange-tip is one of the species to spend the winter as a pupa, overwintering in tall vegetation somewhere close to the foodplants upon which it will have fed as a caterpillar; these include Cuckoo flower (Cardamine pratensis) and Garlic Mustard (Alliaria petiolata). Other foodplants are sometimes used, including garden favourites like Honesty (Lunaria annua) and Dame’s Violet (Hesperis matronalis), although the survival of the caterpillars on these plants is thought to be poor. One of the most striking things about the Orange-tip life-cycle is that although most adults emerge from pupae come spring, some are thought to delay their emergence by one or even two years. While this unusual behaviour has been recorded in captive-reared stock it has not yet, as far as I am aware, been demonstrated in the wild. One could imagine how the ability to delay emergence might be a useful survival strategy if faced by unfavourable springtime conditions.

While I am always keen to record my first Peacock or Comma of the year, I tend not to think of them as this year’s butterflies because they will have been on the wing since last autumn, visiting late season food sources to lay down the fat reserves needed to get them through the winter. This is why it is the sight of the first Orange-tip of the year that really gives me a buzz, a butterfly signal that spring is well and truly with us.

Many readers will only be aware of the male Orange-tip butterfly and will have never knowingly seen a female. This is because it is only the male that sports the orange, fingerprint smudges of colour on the wing tips that are so characteristic. Females are more subdued in their appearance and resemble our other whites, though the strongly patterned underside of the hind wing, with its grey-green splodges, is a very useful feature to look out for. Large Whites and Small Whites are also on the wing from April, so do take a closer look at any ‘small’ whites that you see in case they turn out to be a female Orange-tip.