April 20th

The easterly winds picked up considerably overnight but luckily Mannez Quarry reserve offers enough shelter  to open a couple of nets despite the strong winds that ruled out Essex farm and Longis reserve. 20 Birds processed included  a Lesser Whitethroat, Sedge Warbler, 2 Whitethroats, 7 Willow Warblers 6 Blackcaps and a Chiffchaff. Birding from the reserve hide between net rounds was most productive. 4 Green Sandpipers (a species considered ‘occasional in Spring’ by Sanders ‘The Birds Of Alderney’) dropped in at about 0700hrs and were at home feeding along side a single Snipe. 8 Swifts passed over and 3 Ring Ouzel flew low across the quarry but headed through towards the higher ground. A female Common Redstart was also taking advantage of the sheltered corner of the quarry but eluded the nets.

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4 Responses to April 20th

  1. Glenn Allen says:

    Quick question,
    On average how many birds caught in the net are ‘repeat offenders?’ That is, ones that have been caught before and already ringed?

    • Hi Glenn. We call ‘repeat offenders’ retraps. We are getting very few retraps during Spring migration as the vast majority of the birds are passing through and not hanging around too long. We have certainly recorded that some of the retraps we have caught a second time this Spring have on initial examination had very little fat and muscle and hence been under the expected weight. Recatching said birds has allowed us to see significant weight gains so Alderney is clearly supplying the birds the food sources they need in order to refuel and continue thier journey. Local resident birds tend to learn quite quickly where the nets are and avoid them though it is always good to re catch them from time to time to determine the birds breeding condition and longivity. Without making exact calculations I would guess that we are retrapping less than 5 in 100 migrant birds and maybe 10 in 100 residents (though it will only be through long term ringing we can determine which the resident birds are) The most significant retraps are what we call ‘Controls’. That is a bird visiting us here on Alderney that has been ringed elsewhere. These are the records that we can learn most from by way of the birds migration movements where they have come, what route they are taking and where they end up and how long they took to get there ! We have now had 11 such birds since 4th March including individuals ringed in Spain and France. I will in time be publishing the controlled birds details and mapping in this site. Hope that covers it for you.
      ABO Warden.

  2. Paul Veron says:

    Very informative as ever thanks John! 🙂

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