Thursday, 20 March 2014

Spring has sprung – wildlife records and the shifting seasons

According to Google’s latest doodle, spring begins today, 20 March, in the northern hemisphere. At CEH we tend to follow the Met Office seasonal definition* which lists 1 March as the start date. Whichever way you look at it, spring-like weather has been seen in many areas of the UK over the last couple of weeks, and our natural environment is beginning to react.

Primroses. Photo on Flickr by anemoneprojectors used under
Creative Commons licence.

Many of the environmental records held at CEH have been crucial in tracking the start of spring over recent decades. As a result we tend to get lots of questions at this time of year along the lines of:

  • "Which species have been seen so far?"
  • "How does 2014 compare to previous years?"
  • "Is there anything unusual happening?"
  • Finally, the big one, "Is it spring yet?"

To answer these questions we turn to our national experts and our long-term large-scale datasets. Scientists across CEH work on a broad range of species ranging from invertebrates through plants to seabirds. Much of the work is at the broad national scale, but we also get detailed field observations sent to us, particularly via the 80+ wildlife recording schemes and societies that are part of the Biological Records Centre.

Earlier this week I asked some of our ecologists to tell me about their latest ‘spring’ related projects and observations:

Dr Stephen Thackeray is leading a project on shifting seasons. He writes, “Over the past few decades we have seen that, on average, many signs of spring have been occurring earlier in the year. However variable weather conditions mean that, in any single year, the timing of these natural events may be relatively early or late compared to this long-term change. We are currently investigating differences in the sensitivity of many of the nation’s favourite signs of spring to changes in temperature and rainfall, to better understand the reasons behind these long-term patterns of change in UK freshwater and dry-land environments, and in our coastal seas.”

Dr Michael Pocock, an ecologist in the Biological Records Centre at CEH, said, "With the milder weather over the past few weeks, queen bumblebees have been emerging from hibernation and beginning prospecting nesting sites. I’ve seen buff-tailed bumblebee (Bombus terrestris) and tree bumblebee (Bombus hypnorum) queens out already. Plants like sallows (with their pussy willow catkins) and winter-flowering heathers (in gardens) are important early sources of nectar for these bees.

"They will be establishing their nests and will produce workers later in the year. It is these workers that will be counted by thousands of school children and other participants for a ‘citizen science’ project later in the year, seeking to look at the effects of our landscape on bumblebee diversity.” The project Michael refers to is the Big Bumblebee Discovery.

7-spot ladybird, photo Helen Roy

Dr Helen Roy, like Michael an ecologist in the Biological Records Centre at CEH, has a particular interest in ladybirds. She also co-leads the UK Ladybird Survey. In 2014, the survey has already received reports of many of the 46 species of ladybird in the UK including the 22-spot, harlequin, the Adonis ladybird, 11-spot, cream, orange, heather, 16-spot,  10-spot and even the very rare 13-spot ladybird.  There’s also been lots of 7-spots reported, which is excellent news. Dr Roy is often asked about the impact of the alien Harlequin ladybird on the UK’s native species which include the 7-spot and 2-spot.

She says, “In 2012 harlequin numbers were slightly reduced because of the dreadfully wet spring and summer. In 2013 the spring was slow to get going but the fantastic weather through July and August enabled the harlequin to increase in numbers. This alien species can continually reproduce throughout the warm weather and so has the advantage of getting through a couple of generations per year. In contrast many of our native species have only one generation per year. So the high numbers of harlequins are a consequence of a good summer - favourable weather and lots of food (aphids).

"In contrast 7-spot ladybirds didn't fare so well last year but, so far, the numbers of records received by the UK Ladybird Survey in 2014 are encouraging. So although there were fewer 7-spot ladybirds around to overwinter  through 2013-2014 compared to 2012-2013, a good number have survived. Tens of thousands of people have got involved with the UK Ladybird Survey and their observations contribute enormously to our understanding of ladybird ecology."

Finally, Dr Marc Botham, who works on the UK Butterfly Monitoring Scheme,  gave me some butterfly information. As expected all the UK butterfly species that overwinter as adults were seen very early in January this year given the mild (if rather wet) weather in the South. Within the last two weeks as the sun has come out there have been observations of various 'spring' species including Small white, Large white, Holly blue and Speckled wood. More can be found on the first sightings page.

Speckled wood butterfly, photo: Shutterstock

The best way to record your wildlife observations is via iRecord.  It’s time to get outdoors and get recording!

Barnaby Smith 

Additional information

*Met Office: When does spring start - the difference between the meteorological and astronomical seasons

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