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what is this for?

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Offline lucy

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« on: April 04, 2007, 16:57 PM »
Wasn't quite sure which thread to put this on, as the purpose of the object is a mystery.  One part of the Collserola park outside Barcelona is privately owned, although not efficiently fenced off and various trails cross it.  In this part of the woods there are several of these nest boxes tied on to trees at only about a metre off the ground and with pipes stuck into them.   Has anyone ever seen anything like this before?  Any ideas as to what they are doing there?

Offline Dave

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« Reply #1 on: April 04, 2007, 17:47 PM »
Dear lucy
The nearest thing I can find, is on this webpage, described as suitable for birds, Mammals, and reptiles
http://www.mulchnet.com/image/Nest%20Boxes/Std-box.jpg
Regards
Dave

Offline lucy

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« Reply #2 on: April 04, 2007, 19:41 PM »
What mystifies me, Dave, is that the boxes have been hung so low and very near the path.  This part of the wood is privately owned but once a month the gates are opened and people are allowed in.  I can’t imagine what bird would use such easily accessible nesting sites.

Offline Sue

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« Reply #3 on: April 04, 2007, 22:35 PM »
Hi Lucy,

very intriguing! Are all the tube extensions exactly the same? I wondered if they were different, as then maybe they were testing a design to inhibit access to the creatures that would otherwise rob from the nests. The low level for easy check ups of the design.

Failing that it must be a central heating/cooling system!

Regards, Sue
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Offline lucy

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« Reply #4 on: April 05, 2007, 17:31 PM »
Sue, your idea of someone carrying out a study has led me to the answer, although it's not the nest boxes that are being tested. Googling led me to the Barcelona science museum web page, and a biology paper on pigmentation in bird plumage!  It describes how nest boxes were used in this area to periodically trap Great Tits.  The tubes are "funnels" - it seems once the birds are tempted inside they can't get out.  I just hope they were analysed and set free really quickly. Skimming through the paper I saw that some individuals were recaptured - poor things! - allowing the researchers to notice any changes. But that would mean the birds weren't harmed by the experience.

Offline Clive

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« Reply #5 on: April 05, 2007, 18:02 PM »
Hola,

So if they are still in place on the trees is there a way you can check to see if they have been de activated somehow? Like maybe there is a door that closes to stop the birds getting in.

It is a bit worrying that the traps are still there when it seems no one is checking them every hour. I know that ringers who use nets check them very often and then take the nets down when they are finished so why are these traps still there?

Can you post the link to the web page for us to look at?

Clive
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Offline lucy

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« Reply #6 on: April 05, 2007, 19:45 PM »
Here's a quote from the BCN Museo de Ciencias Naturales web page, which only appears in the cached version.

(their address:  http://w10.bcn.es/APPS/wprmuseuciencies/Museu.GeneradorPagines?idioma=2)

"Can Cata is located on the north face of the Serra de Collserola facing Cerdanyola. The study area, is located between 85 and 200 metres above sea level, and is occupied by forests of Aleppo pine (Pinus halepensis) on the mountainsides, which are considered to be poor quality areas of habitat, and a mixed forest of holm oak (Quercus ilex) and common oak (Quercus cerrioides) at the bottom of both valleys which is a high quality area. The site covers a 100-hectare area in which 200 nesting boxes have been set up. The study species in this area is the great tit."

But this seems to refer to genuine nest boxes, not traps.

The following is the link to the paper about seasonal changes in plumage coloration, which mentions the funnel traps.  It's an html text.  If the link doesn't work - it looks so long! - google "can cata great tits" and it should be the second one down.

Next time I go that way I'll stop and take a closer look at the boxes - they've been there for at least a year.  You're not supposed to go through that bit of the wood unless they open up the big gates. But one side of the area has no fence what so ever, and if you're following some of the Collserola trails you don't even realise you've entered private property. 

http://66.102.9.104/search?q=cache:7ZsUuxi7eVIJ:www.bcn.es/museuciencies_fitxers/imatges/FitxerContingut5373.pdf+can+cata+great+tits&hl=en&ct=clnk&cd=2&client=firefox-a

Offline lucy

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« Reply #7 on: April 07, 2007, 10:37 AM »
Had a look inside one of the boxes and found an old nest inside!  The funnel traps mentioned in the paper must have been something else.  I’m amazed that birds would use such accessible nest boxes.  Sue’s idea of an anti-predator device must be the right one.  These woods reverberate with woodpeckers!  I once saw a film of a woodpecker peering inside a box and proceeding to do some woodwork to widen the hole.  It was shot from a fledgling’s perspective and was like a horror film.

I still wonder about the purpose of the plastic ring placed at the end of the tube, though.