On Tuesday morning I left the builders to finish off our bathroom upgrade and went in search of another set of British Builders, the Sand Martins at our Cockerham gravel pit colony.
Sand Martins build their nests at the end of tunnels up to four feet in length, the passages bored into sand or gravel by using their beak, feet and wings. Sand Martins are very sociable in their nesting habits whereby anywhere between a dozen and several hundred pairs nest close together in the likes of sandy river banks, cliffs or gravel pits.
Sand Martins build their nests at the end of tunnels up to four feet in length, the passages bored into sand or gravel by using their beak, feet and wings. Sand Martins are very sociable in their nesting habits whereby anywhere between a dozen and several hundred pairs nest close together in the likes of sandy river banks, cliffs or gravel pits.
This species is unusually difficult to monitor, because active and inactive nest holes are hard to distinguish, and because whole colonies frequently disperse or shift to new locations as suitable sand cliffs are created and destroyed by natural causes, occasionally by interference or even on occasion by predation.
Sand Martin colony
Although the Cockerham colony is not huge it is certainly the biggest in the local area. On preparatory visits for 2015 in the latter part of May we estimated 100+ nest holes and approximately 200 Sand Martins in the immediate area. A week or two later and in early June Andy, Craig and I went on to catch 85 mostly adult birds during a ringing session. Tuesday was the follow-up visit and Andy and I reckoned there could be a good number of fresh juveniles ready to be ringed plus a chance of capturing more adults.
Sand Martin
Today we totalled 88 birds comprising 62 new birds, 5 birds previously ringed elsewhere (controls) and 21 recaptures from our previous visit of 12th June. Of the 62 new birds, 18 were juvenile birds and 44 adults. The five “controls” all bore rings beginning Z401, the similar numbers far from coincidental as we are sure they were ringed by other ringers at Sand Martin colonies about 20/25 miles to the north along the River Lune.
Sand Martin
Catching and processing 88 Sand Martins kept the two of us busy but in between times the other birds we saw included 2 Common Terns overflying the water plus resident Canada Goose, Mute Swan, Moorhen, Coot and a number of breeding Oystercatchers. One pair of Oystercatcher has a late nest containing 2 eggs in a very busy part of the farm where only time will tell if their gamble pays off.
Oystercatcher nest
Oystercatcher
The approximately 250 Sand Martins on site vastly outnumbered the few Swallows in residence around the farm buildings.
Swallow
More news and views of birds soon. In the meantime I'm linking to Stewart's World Bird Wednesday.