Bob Jarman discusses declines in some well-known bird species.
They used to be regular visitors to my garden bird feeder. Last year they were common across the city, so where are all the chaffinches?
Local birdwatcher and expert on woodland birds Richard Broughton said: “I surveyed 230 hectares of local woodland in Cambs and counted zero chaffinches. In the same week 10 years ago I counted 36 singing males.”
A recent breeding bird survey in the Thetford Forest recorded only one chaffinch and it should be a common bird.
Our city chaffinches seem to have disappeared too, and I’m not the only Cambridge birdwatcher to have noticed this. I heard only one singing this year in Logan’s Meadow and a single bird in woods near Madingley.
For many years greenfinches declined dramatically. The reason was the spread of trichomonosis, a fatal protozoan disease caught at bird feeders, and greenfinches were susceptible.
The RSPB encouraged everyone to clean their bird feeders regularly and greenfinches seem to have recovered. Perhaps the same disease is affecting our town chaffinches which often use garden feeders, and this is being transmitted to birds in the wider countryside?
Richard has also documented the extinction of the marsh tit from nearby Monks Wood. Despite its name, the marsh tit is a woodland bird.
During the last 55 years its population has declined by 80 per cent. Hedge lines between woods are essential for local movements to diversify isolated woodland populations. It breeds in Madingley Woods and the removal of the belts of trees for the proposed busway may cause the extinction of this local population.
The latest findings from the British Trust for Ornithology’s (BTO) heron survey shows a decline in breeding numbers. Herons may soon be added to the Birds of Conservation Concern Amber List.
I have not noticed this decline locally. There is a regular heronry in Newnham and one or two nests elsewhere, making about 12 breeding pairs in Cambridge. Perhaps this decline is due to fewer fish in our polluted fresh waters.
The first confirmed breeding of Cetti’s warbler was in Kent in 1973 although birds had been heard in Dorset since about 1968. It has now expanded its range north to southern Scotland. It is a warbler of dense thickets in ditches and marshes and the most difficult bird to see!
I have heard it this year in Ditton Meadows and two at Paradise Nature reserve. Last year I heard it on Coldham’s Common near United’s football ground.
You hear Cetti’s warbler rather than see it. It shouts its presence with an abrupt outburst, once heard, never forgotten! It is a non-migratory warbler and susceptible to cold winters.
It looks like a reed warbler but lays bright red eggs which may be a defence against cuckoo brood parasitism. Cuckoos regularly lay their eggs in reed warbler nests and can disguise their eggs with the mottled egg pattern of reed warblers, but it seems they can’t match the bright red of a Cetti’s egg.
I saw my first Cetti’s warbler in 1969 at Radipole Lake, Weymouth. I was pillion on my best friend’s BSA 250cc motorbike. On the way home we stopped at a café with a row of Triumph 650cc and Norton Commando 750cc motorbikes parked outside.
While drinking our cups of instant coffee (no coffee beans then!) William decided to play the jukebox with some heavy rock music. To our horror he pressed the wrong selection buttons and on came Summer Holiday by Cliff Richard. About 20 pairs of eyes glowered at us. We decided to leave, fast!
The wettest March on record and persistent northerly winds in April resulted in a hesitant arrival of spring migrants: sand martin on 20 March and wheatear on 21 March.
Local highlights included a firecrest singing in Herschel Road, a remarkable sighting of a bluethroat near Grantchester Meadows, up to five wheatears at Hobson’s Park, early swifts from 21 April, garganey ducks at Granchester Meadows, common sandpipers near the Cantabs Rowing Club and Milton Country Park, a hobby over Logan’s Meadow, a willow warbler in Mill Road Cemetery, white storks over Magog Down and Milton, and the continuing success of the breeding peregrines in the city centre.
