Cold and late ‘Victorian’ spring left baby birds dying of hunger
Slow emergence of leaves in conditions more typical of 19th century led wildlife to get nesting times wrong
SPRING in the British countryside this year was typical of the late Victorian era in the timing of the key indicators of the season, prompting fears about the effects on birds.
The early signs of spring, such as sightings of swallows, are first seen on the south coast and then usually progress to the far north over a threeweek period, which equates to spring sweeping northwards at 1.8mph. But this year, spring took four weeks to move to the north, a speed of 1.2mph.
Experts have warned that the slow development may have seriously affected nesting birds, causing some broods to starve to death.
Dr Kate Lewthwaite, a citizen science manager at the Woodland Trust, said it was “without question” that some species of bird, which rely on leafing as an indicator of when to brood their young to ensure a steady source of food, would have been affected.
“Wildlife reacts to the arrival of spring flowers and trees,” she said.
“Whilst the analysis perhaps throws up more questions than it answers, it does highlight how delicate the balance between success and failure is for a number of species.”
The analysis, which was completed by Prof Tim Sparks at Coventry University, suggested that the delayed spring was due to the country experiencing a mild December before a cooler start to this year.
Greg Dewhurst, a forecaster at the Met Office, said temperatures were more than 35.6F (2C) above average this winter at 44F (6.7C), before dropping in March to just below the norm.
“On some days in March and April the temperatures were cooler than in November and December,” he said. “In terms of this cooling, I can see how this may have created a delay.” Ben Andrew, a wildlife adviser at the RSPB, said that the charity had received a higher than usual number of calls about birds suddenly dying in their nest boxes.
“Whole broods have died, sometimes even overnight,” he said. “It is not the case that the parents are abandoning these boxes, they have just timed it slightly wrong.”
Mr Andrew said that species may have been fooled into preparing their nests too early because of the warmer winter.
“They have nested and mated in the slightly warmer period,” he said. “They were fully committed but when the chicks hatched, the temperatures plummeted and the rain washed crucial food such as caterpillars off leaves and trees.”
Rare species, such as turtle doves and nightingales, could be affected in the long term by this year’s delayed spring, while migrant birds, including swallows and swifts, are thought not to be breeding at the same rate as before, Mr Andrew said.
The analysis, which was released today, used signs including sightings of frogspawn, orange-tip butterflies and oak leaves to determine the “rate” of spring. It put the arrival of the season this year in line with averages from between 1891 and 1947.
Records from the Woodland Trust’s nature’s calendar scheme showed this year’s development was much slower than the 1.8mph seen on average between 1998 and last year.
Experts said that the slower spring could not yet be put down to climate change because further seasons would have to be looked at to determine if there is any trend.