Weka chicks in traps - how to avoid?

[Dave Houston]

Mike Ogle from Takaka posed this question;

Have you had small weka chicks killed in traps (in tunnels) and found a way of stopping this happening?

If so, could you let me know what your solution was please.

We are reintroducing weka to Totaranui, and initially this was not a problem.  But now that numbers are building up we have caught 1/2 dozen very small chicks (2-3weeks old?).  No problem with adults and larger chicks.  We have been closing traps for a few weeks around where small chicks are seen - but as numbers build up this is becoming impractical.

Our current set up is DOC 200s in wooden tunnels. Mesh baffles on ends and one inside adjacent to trap.  Distance from outside baffle to trap 300mm, hole in outside and inside baffle 60mmx60mm.

Suggestions so far have been: a length of downpipe (60mm,80mm diameter?, length 150mm?) or place the trap on a log to raise it off the ground 3-4inches.  Weight of chicks is probably not far off weight of a smaller stoat - so can't use a difference in trigger weight.

Below is a reply from Pete Gaze of Nelson;

I know your trap box design and how well it has excluded adult weka.

As for the weka chicks - I think that either of the 2 proposed solutions should work.  A couple of 4x2 spacers under the box would be a big deterrent to chicks - particularly if the spacers are back a bit under the floor of the box so that there was no 'step' up.  I have always been a fan of PVC pipe entrances - set at right angles to the line of the box - but would involve major modifications to the box.

I presume that the chicks are not being attracted to your egg bait - rather just being curious.  Nevertheless, you may want to swap to Erayz polymer baits that would provide no visual attraction.  Chris and Kate have been using these as a field trial comparison.

On the other hand - wonderful that you have achieved the most successful mainland weka translocation!

Anyone else have any suggestions for Mike?

[Dave Houston]

And this from Colin Bishop

Hi Mike I had the same problem with banded rail on Matakohe-Limestone Island. 
 
You could try putting a low ceiling in the trap between the entrance and the baffle.  Birds need to stoop and then stand up to get through the entrance hole, a low mesh ceiling, level with the top of the hole, would prevent this.  When constructing the traps and cutting the entrance hole in the mesh you could try leaving the top of the hole attached and bending it inwards.

[Dave Houston]

A couple more extracts from another email chain on the topic;

I'm trialling a retro-fit weka proofing to DOC150 stoat tunnels.  Originally had 60mmx60mm holes in the mesh at ground level (mesh at entrance and again at a baffle just under 300mm from the entrance, plate at least 300mm from entrance hole). We caught several weka chicks in this set up so stapled mesh over the original holes at ground level and cut new 60mmx60mm partway up the entrance (probably about 80mm above ground level).  This has stopped weka chicks wandering in - still appear to get plenty of rats but I need to get more data before I can determine of there has been a reduction in stoat captures. Have had one chick get through the new set up, but was probably a result of Yorkshire fog forming a mat up to hole level at the entrance.

cheers

Mike Ogle

And this from Rosemary Cotman of WekaWatch Kawakawa Bay

It is not clear from the emails whether these people are using the recommended weka safe tunnels - extra long wooden boxes.  The ones Mags Ramsey is using for the dotterel program are the short ones but she is outside our weka area.  Not sure what will happen if our weka get over that way the first bay at kawakawa Bay band towards Mataitai..

We have about 60 weka-safe boxes out with either 200 or 250 traps in them.  Entry size is 60 by 80 - interestingly some are 80 high and some are 80 wide.  I have not tried to analyse whether the two different orientations make a difference.  Some have been out for more than two years which is a fair test I would think.

Our catches to date (clearing the traps monthly) are 118 hedgehogs,170 rats (mostly ships). 7 stoats, 4 weasels and two ferrets plus by-catches of one myna, one mouse, two feral kittens and surprisingly since the bait is freeze dried rabbit, one rabbit!  No weka and no weka chicks.

Of interest is that all the mustelids except for one of the two ferrets were taken in 200 traps rather than 250s.  one ferret succumbed to a cracked egg as bait and the other freeze dried rabbit.

Our very first catch when we had only 5 traps was a hedgehog that weighed 710 grams - a whopper!! and it had got through the standard 60 by 80 entry hole.

We did an experiment here off the deck in our 'garden' with training our habituated weka to feed from a trap box with the standard sized entry (trap NOT set of course) - whole grain oats - and I attach a photo of the pattern left after the weka had been.  We have now opened the entry to 80 by 80 and the treadle still can't be reached by an adult North Island weka (smaller we understand than the South Island sub-species) but we are waiting till we get some chicks to test that too.   

[WekaWatch Kawakawa Bay]

Further to our message above - I have checked the length diagonally from first entry baffle to the one right by the treadle and it is 300 mm.
We work closely with Tony Beauchamp, (DOC Whangarei) who we regard as our weka guru.  He commented that weka are visual and mustelids work by smell so that any entry that was out of line of sight of the bait would be more likely to deter the weka.  We have not had to modify our traps yet but with only 60 to work on and a few good volunteers we could do a side entry plastic pipe entry if we needed to.  Even using the 60 by 80 entry we have already we could extend the tunnel length with a piece of pipe held outside the tunnel with a long wire staple.
We were talking to someone yesterday who has been stoat trapping in Fiordland - a huge number of DOC traps, can't remember how many.  He says that nails partly driven into the floor of the entry tunnel would allow a stoat to weave its way in to the treadle while a weka could not wiggle its neck from side to side and still reach the treadle. Would this deter a chick??