Wednesday, 7 November 2012

The Cattle Point Entrance Oaks Effect

Why not start our own local version of the Patagonia Picnic Table Effect?  For those not familiar with the phenomenon, it apparently spans back to a rest area in Patagonia back in 1971.  Some birders stopped in for lunch and ended up finding the first record of Black-capped Gnatcatcher north of Mexico.  A swarm of birders descended on this little rest area and consequently turned up the first North American record of Yellow Grosbeak, as well.  The Patagonia Picnic Table Effect now refers to any instance where an unusual bird is reported and those looking for the rarity turn up another stray.

This phenomenon occurred locally on November 1st when Ian Cruickshank put out the word that he had briefly observed a Tropical Kingbird (Tyrannus melancholicus) in the oaks at the entrance to Cattle Point.  Several birders quickly launched into action to try to relocate the kingbird.  Steven Roias tried in vain to find this once-every-couple-years rarity from the south, but he did find a tern feeding just offshore.  He jotted down some detailed notes on the bird and left thinking it was just a Common Tern (Sterna hirundo), which is actually a decent bird here these days.  When he got home and broke out a field guide, he realized all the features he had seen did not add up for Common and were bang on for an Elegant Tern (Thalasseus elegans)!

Elegant Tern on the rocks off Bowker Ave. in Oak Bay, taken on November 2, 2012 (Photo: Daniel Donnecke)

The next morning, Daniel Donnecke and Val George were on scene and managed to relocate the Elegant Tern on the rocks at the end of Bowker Ave.  This news made me very anxious because I was working and the feeling was so overwhelming that I buckled and went out to search for the bird.  I decided to head right to Bowker Ave.  When I arrived just over an hour after the morning report, not a soul was in sight.  I raised by binoculars and scanned over to Cattle Point and could see a scope set up and a group milling around it.  I hopped back in the car and raced over to the point.  I was greeted by Aziza Cooper who said the bird had flown south and seemingly landed behind one of the islands.  I looked over at the rest of the group and they were intently looking at something.  Barb McGrenere waved over to me and I thought it was just a "hello" wave, but then Mike McGrenere announced "The tern's over here!"  I darted over and set up the scope just in time to not see the tern.  So I played the waiting game.  I waited for over an hour and kept checking my watch.  I had intended to be back at work at 1 p.m. and that time was approaching rapidly.  I decided to cut my losses at Cattle Point and put in quick check at Spoon Bay and Cadboro Bay, the latter being the assumed destination of the tern as it went out of view to the north.

I scanned the rocks in Spoon Bay and checked every passing Bonaparte's Gull (Chroicocephalus philadelphia), but no sign of the tern.  I was going to head to Gyro Beach, but as I passed Loon Bay I noticed several Bonies and figured it was worth a check.  A scan out beyond Loon Bay into Cadboro Bay revealed a lone adult Snow Goose (Chen caerulescens), but again no tern.  I was starting to pack up when I noticed multiple birders that I had been chatting with at Cattle Point had decided to check here as well.  I went over to let them know about the goose and realized I could see a whole new sliver of water from where they were standing.  I set up the scope again as a last ditch effort.  As I scanned out over Cadboro Bay, a bird with a black crown flew through my field of view and I excitedly proclaimed "I've got the tern!"  Everyone there managed to observe the tern circling for half a minute before we lost sight of it as it headed back south towards Cattle Point.  After celebratory high fives or verbal equivalents, I had to get back to work.  I left very happy as Elegant Tern was my 289th Victoria checklist area bird.  Still knocking them down ever so slowly!

So how rare were the two birds involved in the Cattle Point Entrance Oaks Effect?  Tropical Kingbirds are annual in British Columbia and one is seemingly turned up approximately every second year in Victoria.  They are almost certainly annual, but there might be a lack of focused searching in appropriate habitats for this species from mid-October through November.  Elegant Terns, on the other hand, are typically reported during El Niño years.  There is no regular pattern to El Niños, so it can't be predicted when Elegant Terns might put in an appearance in our waters.  Previous records in the Victoria checklist area are surprisingly numerous, but they are the result of several reports in certain El Niño years.  Using the E-Fauna "British Columbia Rare Bird Records" document, Elegant Terns were reported in 1983 (5 records), 1992 (7 records), 1993 (1 record), and 2008 (2 records), with some records potentially referring to the same bird or birds.

The 2012 record of Elegant Tern is anomalously late and may be in part due to a weak El Niño that really started showing effects in September.  Elegant Terns breed in southern California and Mexico and then have a brief northbound dispersal.  The late summer arrival of Heermann's Gulls (Larus heermanni) in our waters is due to a similar pattern.  Elegant Terns typically only head as far north as northern California before they turn back south and head to South American shores from Peru to Chile.  The warmer ocean temperatures during El Niño years draw southern marine life northward, and Elegants Terns follow suit with this trend.

I was more interested in catching up with the Elegant Tern because the really pronounced El Niño years occurred before I was in the habit of consistently chasing rarities.  As a result, I haven't had much of a chance to see one locally.  I was, however, fortunate enough to see my lifer Tropical Kingbird way back in 1998 at Esquimalt Lagoon.  I certainly wouldn't have passed up a view of the Tropical Kingbird that Ian found, but I can wait for the next one or just be content with the hundreds I've seen in the Neotropics.

I'll just wrap this up with a congratulatory note to Ian Cruickshank for finding the Tropical Kingbird and initiating the Cattle Point Entrance Oaks Effect, and Steven Roias for completing the phenomenon with his sharp eyes and detailed notes leading to the identification of the Elegant Tern.  What's next?  The Swan Lake Lollipop Boardwalk Bonanza?  The Esquimalt Lagoon Hump Hoedown?  The Whiffin Spit Breakwater Blitz?  The Island View Beach Boat Launchapalooza?  Whatever goes down, I look forward to catching up with familiar faces and sharing some laughs.

1 comment:

  1. What about the Rocky Point Banding Effect (sorry--could think of a better idea)?