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

The Daily Telegraph - - News - By Ly­dia Willgress

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.

The de­layed spring could af­fect rare species such as nightin­gales, as it dis­rupts their breed­ing pat­terns

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