Peter Karsten,with the help of Kevin Behrens, Frank Frketich and Laura Pope recently converted the 6 fixed purple martin boxes at the community dock to be on a pulley system for cleaning the boxes and banding the Chicks. They had to set up scaffolding to do this previously which would not work for banding because of the long, complicated set-up time which would be an intolerable disturbance to the birds.
They are also cleaning the two boxes on the dolphins close to the ferry ramp today at low tide. Both boxes were occupied by Purple Martins last year; one box raised chicks. BC Ferries is going to remove these dolphins to make room for the cable ferry construction. That should only be done after any chicks have fledged.
Bruce Cousens comments:
Thanks Peter for the upgrade, update and photos – great job! I agree that the use of a ladder against the 4″x4″ post for access was unsafe – we considered it last summer, but since there was no sign of PUMA nesting activity at those boxes (and our short ladder wasn’t quite long enough for access anyway), we decided not to take the risk. We use a similar cable-and-pulley approach with our experimental “pole and sliding sleeve system” (with 4-6 nest boxes and a light winch) for low-impact manual installation in wetlands and similar sensitive habitats, though I used a different off-the-shelf hardware solution (stainless threaded hook) to mount the 1″ stainless upper pulley.
I was going to suggest not cleaning out the nests in the boxes on the pilings this year – they’re new last season and should be okay for re-use for another year (unless they’re badly fouled, wet and rotting, or infested with fleas and/or nest mites) – but no big deal… Please place a generous handful of similar light twiggy material (coarse straw or dried woody or reedy material from the back of the beach works okay, but not grass) in a low platform or shallow cup at the back of the empty boxes when you have time and another opportunity for access. We normally leave clean dry parasite-free nests for another year and add some clean nest material when we decide a nest should be replaced. This may be particularly useful for attracting birds to new colony sites, and I have had good success getting subadults to quickly claim, occupy, add a green leaf lining and start laying eggs in roughly formed nest material in new boxes.
It appears martins, as secondary cavity nesters, like to re-use (their) old nests, to which they will add new material each year – both early-returning adults and later-returning subadults seem to prefer boxes with used or new nest material over empty boxes, if available. This is likely because it saves them nest-building time and effort (triggered by day length), which competes with foraging time and is often neglected in adverse weather when food is scarce, then can result in eggs being laid with little or no nest when sufficient food becomes available (likely regulated by fat reserves needed for egg production). In years with favourable early spring weather there’s sufficient time for both nest building and feeding, but with a prolonged cool wet spring here at the northern limit of their breeding range, there may be an interaction effect and a pre-existing nest may provide them an advantage. We tend to think of used nests as junk, but in martins and some other aerial insectivores they may actually be a valuable resource. They even seem able to deal with some potential nest parasite problems – we often find empty used nests with heavy bird flea infestations in winter and spring, but rarely find fleas (let alone heavy infestations) in an active nest with young.
Whether young in the boxes on the pilings are fledged by Aug. 15 depends on whether they are occupied by adult or subadult birds, as well as the weather… Earlier-arriving adult birds will nest earlier than subadults with favourable early spring weather, but egg production can be delayed for up to a month in adverse weather until they have enough food to build up sufficient fat reserves for egg production. The same is true for later arriving subadults to a lesser extent, so nesting timing is a function of weather and food availability, and equally difficult to predict in advance. This is quite different than for most of our other familiar songbirds (smaller swallows have a shorter nesting cycle and can raise multiple broods if the first one fails). In general, adult nests should have young fledged by Aug. 15 in most years, but subadult birds may not fledge young until towards the end of the month, so a later target date for the disturbance would be preferable. Last year there was one early adult nest (fledged 4 young ~Aug. 11) and one later subadult nest (failed, but eggs would have hatched ~Aug. 2 and young would have fledged ~Aug. 30) and this is the most likely pattern again this year. As well, martins bring their young back to their nest box (or a nearby box) to roost at night for ~7-10 days after fledging, though if the nest boxes are disturbed or removed at this point, they will find other night roosting sites, but return the following year may be less certain.
It would be great if BCF could just move (or more likely replace) the pilings further along the beach in a suitable area for re-use, assuming there are no problems with permitting, etc. The main issues involved are getting the pile driving equipment on site (expensive, so you want to make use of it while it’s there) and any permitting concerns – the pile driving takes only a few minutes once the rig is in position. BCF has been very supportive re: the colony site at Buckley Bay and is sensitive to public interest in the birds, so they may be willing to help out again if it’s popular, cheap and easy.
Cheers, …Bruce
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Bruce Cousens, B.Sc., M.Sc., R.P.Bio., Senior Biologist,
BC Purple Martin Stewardship & Recovery Program Coordinator,
Georgia Basin Ecological Assessment and Restoration Society
PO Box 41012, RPO Woodgrove Nanaimo, BC, V9T 6M7
Phone/msg./fax: (250) 758-2922; E-mail:
Not only does the martin have these food-seeking predators to watch out for, it also has to contend with two enemies that aren’t even out looking for a meal but are just trying to steal the nesting sites from the martins. The two birds that have been most detrimental to the existence of the martin are the European starling and the English house sparrow.