Thursday 19 May 2022

Bird predation

The recent posts about birds getting into light traps reminded me of the time when a pair of Great Tits, had worked out how to get in and out again (of a Robinson). I cured the problem by buying a large rubber spider from a joke shop, which I suspended from underneath the bulb holder with string. The prospect of getting past something that big with lots of legs wobbling about inside the trap was evidently considered too much of a personal risk. Those not skilled in welding may wish to consider this as an alternative!

Bird predation in traps is rare but usually occurs when they are feeding young. The same goes for outside the trap. During the first 2020 lockdown, one morning I was sat on a stool on the patio going through the trap. A Blackbird who was being followed around the garden by a vociferous fledging, simply ran around me and picked a moth off the accumulating the pile of egg-trays and ran back again. As I turned round it was feeding it to the fledgling about a yard away. In spite of my protests this happened twice before I decided enough was enough and broke off from the catch to shoo them away! Blackbirds tend to be more interested in dry weather when worms are too deep so they have to turn to other things. Last year I had one that learned to glean moths off the wall up to a metre off the ground. 

As Dave says, getting up very early helps and as Peter says I'm sure leaving the lamp running also helps - I have always done this. My Robinson has to run up against the wall of the house in order not to keep neighbours (and my wife) awake. This means there are always moths on the wall and fence, and anything large and conspicuous will get picked off if not moved to a safer place. Not trapping every night also reduces the problem as does releasing the catch as close to dusk as possible (if you can keep in the shade during the day) and spreading them around. You might think they're safe in the flower bed but if a bird finds more than one it will keep looking. 

Regarding the current immigration I had 6 Silver Y and 6 Plutella xylostella last night. Someone reported a Striped Hawk-moth at Whitchurch-on-Thames on Atropos Flight Arrivals the other day. I would be very interested to hear who it was to make sure the record gets captured. 

Regarding the Upper Thames Atlas, as Dave has explained a mountain of work over many years goes into county recording so there is always a time lag. However, looking for the presence or absence of records of a particular relatively common species from a particular square rather misses the point, which is to illustrate the general distribution and abundance of each species in the area. As I'm sure Dave has already pointed out, the rare species are high priority, and new species will be added as soon as reasonably possible. 

Best wishes

Martin Townsend


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