After The Thunder

Monday evening saw thunder and lightning rolling around the area followed by late night downpours. But we stuck to the pencilled in plan and hoped everything would be on song for Tuesday 0630, a visit to the Sand Martin colony at Cockerham. 

Tuesday morning began fine, the rain and thunder long gone to leave a cool, almost idyllic morning at the colony. The 0630 start had left the birds a couple of hours or more feeding time before we intruded upon their space. 

Two previous visits of 17 April and 26 May saw a total of 32 captures, 17 females, 14 males and one indeterminate sex of the April visit. This almost mid-June visit would almost certainly result in a catch containing a percentage of youngsters and thus, together with noting brood patch progress, assessing the breeding success of the colony so far. 

The colony is concentrated in one small area of the quarry face and estimated to be 60/70 active holes, not huge by Sand Martin standards but the only Sand Martin colony for a good number of miles around and therefore a valuable and unique addition to local flora and fauna. 

Sand Martin colony

 

We caught 25 on this latest visit, 12 adults (9 male, 3 female), three of them recaptures from earlier in the year; and 13 juveniles of the year. 

Adult Sand Martin

Juvenile (3J) Sand Martin

 

We sex Sand Martins and many other species by examination of their cloacal protuberance in the case of males, and for females by her brood patch (bare belly) progress. Males of some species develop a partial brood patch that is not as extensive as that of a female, a bare region of the undersides that at the peak of incubation lacks any feathering at all. 

Almost all birds incubate their eggs: keeping them warm while the embryo develops into a chick. In order to transfer heat better from their body to the eggs, many birds develop brood patches (a.k.a. incubation patches). The bird loses feathers from the belly, and the bare skin becomes wrinkly and swollen with fluid. Brood patches are a good way to tell what breeding stage a bird is at, since usually the brood patch begins to develop during nest building, becomes very swollen with fluid during incubation, and then declines. 

Brood patch

 

Juvenile Sand Martins that spend a couple of weeks in their nest tunnels often emerge carrying swollen and unsightly blood sucking hippoboscid ticks that have attached their body parts through feathers and into the birds’ skin. The one pictured below had six such ticks on its head.

Sand Martin

We can remove the insect with a careful grasp of the blood-filled tick using ringers' pliers and then a slow and gentle twist & pull action that releases the parasite. 

A bonus came with the catch of a feisty second summer male Kestrel when it tried to snaffle a Sand Martin but didn't count upon a mist net across it's normal approach line. There was some evidence of predation of the colony by the amount and type of feathers on the ground immediately below the nest holes.

Kestrel

Kestrel

All in all a very successful morning. Back soon with more news and views from Another Bird Blog.

Linking today to Eileen's Saturday blog.

Martins and Hobby

It was 16 June, 8 days before, that we ringed four tiny Avocet chicks. When I telephoned Chris on Tuesday evening to say we’d be along on Wednesday to the Sand Martins he said that the Avocets still had four youngsters. That’s quite an achievement since many wading species that start off with four eggs followed by four chicks can quite easily find just a single one makes it to adulthood. 

The Avocets were close by again, near enough to rattle off a number of pictures before we set up the single net for the Sand Martins. It was quite difficult to get all four chicks together in one frame. 

Avocet chicks

Avocet 

Avocet 

Avocet 

Avocet 

Avocet 

We were joined today by Bryan, an extra pair of safe hands for the tricky job of erecting a net to catch the Sand Martins. Catching Sand Martins proved more successful than 8 days earlier as it became clear that more juveniles were around this week. 

Andy and Bryan 

Sand Martin - juvenile 

The martin nests are located at the end of long tunnels, which can be up to a 1m long into the gravelly sand. The chambers are a hotbed for parasites, mostly blood sucking hippoboscid, louse flies. Although not all chicks have the parasite, where we spot them and where possible, we remove the unsightly ticks by a light squeeze and twist of the tip of the ringing pliers. We then quickly send the chick on its way. 

Sand Martin with parasites 

Sand Martin - juvenile 

We caught 23 Sand Martins, 13 juveniles and 10 adults. A recapture ring number S348922 had been ringed here as a juvenile on 1st July 2017 but not in between those dates. 

We had finished ringing the last martin when we heard the distinctive calls of a Little Ringed Plover flying overhead as it continued in a southerly direction. ‘LRPs’ as they are known by birders have bred on this site. Not in recent years, but in conjunction with the farmer, we are working on the idea of increasing the site's species list.  

Over a nearby wood we saw a family party of 6 Kestrels in the air together, probably 4 young and both parents. It’s not a completely unknown sighting but rather welcome when it happens. 

Better was to come a minute or two later in the shape of a Hobby, the bird attracted into the area by the sight and sound of 140+ Sand Martins. It hung around for a minute or two before flying off south in the direction of Pilling. 

It was a fitting end on the high of a very enjoyable morning.