Starling trap shift suggested


Report prepared for blueberry council indicates summer would be a better time to remove juvenile flocks.


By Judie Steeves T


rapping juvenile starlings in summer may reduce damage in blueberry fields according to a report by Doug Ransome of DBR Forestry - Integrated Wildlife Management.


Ransome’s 56-page report was completed for the B.C. Blueberry Council last fall, with funding from the federal-provincial Growing Forward program, the council and the B.C. Milk Producers Association. After reviewing all available studies and work done on removing starlings to reduce damage to agricultural crops throughout North America, Ransome concluded that winter trapping is not effective at reducing breeding populations or preventing damage to summer crops such as cherries and berries.


However, he did feel that a summer trapping program could effectively remove the flocks of juvenile starlings that can cause devastating damage to crops, although it might take a year or two before it works well. In those first couple of years the focus is on selecting the best sites for trapping and identify key primary and supplemental feeding areas for effective removal of the birds, Ransome explained.


Few adult starlings enter the traps, he reported, so it is the juvenile birds that would be targeted, and there is significant mortality of this group over winter. Summer trapping would simply remove them earlier in the year, rather than making a permanent dent in starling populations.


Trapping should be conducted from May or June through to August. Previous reports have lacked scientific monitoring on which to base decisions, so Ransome recommended the change in damage levels be monitored carefully to


12 British Columbia Berry Grower • Spring 2011


indicate whether the program is successful.


That would also help in deciding on alterations to trapping levels or making other changes to the program to enhance its effectiveness and efficiency.


Few of the previous studies provided a rigorous evaluation of the effectiveness of either chemicals or trapping to reduce the abundance of starlings or damage they cause to agricultural crops, he summarized. For instance, most lacked control sites with which to compare results from either method of reducing populations. However, Ransome felt there is little long-term impact from winter trapping in reducing starling numbers.


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Because of their biology, the birds can re-establish large flocks in winter at good feeding sites after heavy winter mortality, once such control has stopped. Any local control is temporary, he said.


Migrant birds removed with winter trapping would have little influence on spring resident birds, he said.


On the other hand, he said summer trapping does appear to be successful at reducing immediate damage to cherry and berry crops.


Ransome is also an instructor at the B.C. Institute of Technology in wildlife ecology and management.


Doug Ransome


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