Burrowing Owl at Sea Island

The discovery of a Burrowing Owl at Sea Island in November prompted the inevitable discussion regarding its origin. BC's wild Burrowing Owl population disappeared by about 1980 (Leupin and Low 2001) and the very small extant population is attributed largely to annual releases of captive-reared owls. I pursued some research about the BC Burrowing Owl Recovery Program, with specific interest in dispersal patterns and return rates in an attempt to, well, justify counting it. Over the course of my research I realized how little I knew about the Recovery Program, so decided to summarize a few items of interest here.

Mitchell et al. (2011) discuss some of the metrics I was looking for while comparing the success of two releases techniques: hard-released birds (i.e., those released directly in to the wild from artificial burrows) versus soft-released birds (i.e., those released in to an enclosure surrounding their artificial burrow prior to the wild).  Soft-releases appeared more successful with regard to site fidelity, breeding season survival, fledging rate, and ultimately population recruitment (Mitchell et al. 2011). I suspect soft-release techniques will (have?) gradually phase out hard-releases, and therefore will briefly summarize soft-release results only.

The soft release protocol is to place pairs of captive-reared yearling owls inside artificial burrows where they are held overnight before being released in to an enclosure, which is then removed after approximately two weeks. Released owls display high site fidelity, with 86% of released birds (n=140) from 2005 to 2007 staying following their release. During the same three year period, 69 adult pairs produced 168 fledglings, which had a 69% survival rate during a 40-day post fledging period based on a sample of radio-tracked juveniles. Typically, all owlets are captured inside artificial burrows and banded with a USFWS aluminum leg-band and a coloured alphanumeric leg-band when they are four weeks old. Only 5 of 71 (7%) fledglings from 2005 or 2006 returned in 2006 or 2007, resulting in a population recruitment of 0.17 offspring per soft-released pair. The return rate of released adults during the same period was 2% (1 of 62 adults). However, 28% of 'wild' adults (i.e., adults present prior to the annual release of captive-reared owls) returned again in the subsequent year (Mitchell et al. 2011).

Most adult and young owls leave their release sites by October, but there is little information regarding location of their wintering grounds (Mackintosh et al. 2004). One captive-reared owl wintered in Portland, Oregon in 2001 and again in 2002, and another in Port Townsend, WA in 2002 (Mackintosh et al. 2004). In the winter of 2013, a Burrowing Owl wintered in Tofino and another in Comox, but I do not recall if they were banded and whether their origin was determined.

(Aside: anyone interested in the Burrowing Owl Recovery Program and the associated challenges and successes of reintroduction efforts should check out the Burrowing Owl Conservation Society of BC web site).

The Sea Island bird was unbanded, which almost certainly eliminates the possibility of a released captive-reared bird because, presumably, none are missed during banding prior to release. Mitchell et al. (2011) mentions all owlets are banded at four weeks old, but it is uncertain whether the occurrence of unbanded birds at release sites indicates presence of wild birds or simply the progeny of released birds missed during previous banding efforts (Leupin 2004). This, coupled with (limited) knowledge of their dispersal patterns, a juvenile bird from a released captive-reared pair may be a possibility. 

Unlike many larger owls that moult their primaries and some other flight feathers over two or three cycles, Burrowing Owls have a complete pre-basic moult (Howell 2010), which unfortunately complicates ageing this bird relative to large owls that often have striking moult limits in their primaries. I noticed the primary tips looked quite worn and abraded on our owl, but is it too much wear for juvenal feathers? One wise guy quipped "of course they're worn, they live underground", which may be a valid point, but I haven't got enough experience with Burrowing Owls to confirm or deny. 

So, my conclusion: origin uncertain. And that's good enough for me! Every big year needs some controversial tick, and a Burrowing Owl in BC fits that niche quite nicely. 

#258 - Burrowing Owl - 22 Nov 2015 - Sea Island, Richmond, BC

References:

Howell, S. N. G. 2010. Molt in North American Birds. Houghton Mifflin Harcourt Publishing Company, New York.

Leupin E. E. 2004. Burrowing Owl Athene cunicularia in Accounts and Measures for Managing Identified Wildlife - Southern Interior Forest Region V. 2004. BC Ministry of Water, Land and Air Protection. pp. 137-147

Leupin E. E. and D. J. Low. 2001. Burrowing owl reintroduction efforts in the Thomposn-Nicola Region of British Columbia. Journal of Raptor Research 35: 392-398.

Mackintosh, M., E. Leupin and D. Brodie. 2004. Burrowing Owls in B.C. - Science and Stewardship in Action. Proceedings of the Species at Risk 2004 Pathways to Recovery Conference, March 2-6, 2004, Victoria, BC.

Mitchell, A. M., T. I. Wellicome, D. Brodie and K. Cheng. 2011. Captive-reared burrowing owls show higher site-affinity, survival, and reproductive performance when reintroduced using a soft-release. Biological Conservation 144: 1382-1391.

Mock yeah, Ing yeah, Bird yeah

With limited time for blogging, I thought I'd let Harry and Lloyd tell you all about my next year bird.

https://www.youtube.com/watch?v=G5f_gbzo4Q0

#255 + 2. Northern Mockingbird. 21 Nov 2015. Ladner, BC. 

Winter Finches

(N. B.: after 11 months of blogging about my big year, I thought I would attempt to write something at least somewhat educational.) 

My big year recently received a boost from what is shaping up to be a good finch winter. "What exactly is a good finch winter?" you ask. In this instance, "good" is measured from the perspective of a birder, and a winter qualifies as good with the presence of White-winged Crossbills and Common Redpolls. The local abundance of these species varies among years, and some winters none or very few are present. 

Unlike most northern hemisphere songbirds, White-winged Crossbills do not follow the typical north-to-south migration. Instead, they are nomadic, moving in response to the presence of their principal food. Their geographic distribution is closely associated with that of conifers in the genus Picea, and their movements are linked to patterns of conifer use.

A probability of observation (PObs) map for White-winged Crossbill, taken from the BC Breeding Bird Atlas (http://www.birdatlas.bc.ca). The PObs maps are created by incorporating topographic variables into models to make predictions about the likelihood of detecting a species in all areas of the province, within a fixed amount of time (20 hours). Granted this map is based on data collected by atlases during the breeding season, I would still like to point out the 0% probability of observation in Metro Vancouver (click map to enlarge).  

In late June and July, the cones of most conifers are developing and seed inside cones of tamarack and white spruce are among the most accessible. In May, White-winged Crossbills are often on the move as birds search for developing white spruce cone crops sufficiently large to support breeding. White spruce cones shed most of their seed between mid-September and early November. Crossbills generally remain in the area as long as seed abundance is high and leave once it declines, switching then to black spruce. Black spruce cones open later in the year than white spruce and their seeds often remain inside their cones through to the following summer. In late spring, White-winged Crossbills typically migrate from areas of black spruce to areas with developing white spruce cone crops regardless of black spruce seed availability. When the spruce cone crop is poor, crossbills can irrupt into regions south of their usual range in search of good cone crops.

Distribution of three spruce (Picea) species in British Columbia, taken from the Tree Species Compendium (https://www.for.gov.bc.ca/hfp/silviculture/compendium/index.htm). Top to bottom: Engelmann spruce, black spruce and white spruce. Notice any similarities to the White-winged Crossbill probability of observation map?

Though perhaps not quite a full scale irruption, some White-winged Crossbills have turned up on Mount Seymour this winter and were a welcome addition to my year list.

#253. White-winged Crossbill. 20 Nov 2015. Mount Seymour.

While crossbills are nomadic, Common Redpolls are considered ‘irruptive’, meaning they exhibit regular seasonal movements, the extent of which varies between years. One suggested cause behind their irruptive movements is their dependence on birch and alder seeds. Seed shortages may cause redpolls to travel farther from their breeding range in winter, stopping when they encounter sufficient food rather than a pre-programmed destination.

#254. Common Redpoll. 21 Nov 2015. Sea Island.

Redpolls have been reported widely this November, but seemingly from everywhere where I was not. It took some time before finally finding some of my own on Sea Island.

Count Update: 254 + 2 on Nov 21.

Back to Back Birds at Pt. Bob

After a bit of a lull, I got 252 + 1 and 252 + 2 both at Pt. Roberts.

You may recall from an earlier post that there are two versions of the Vancouver checklist area, one which includes the small peninsula of Pt. Roberts in Washington, and one that doesn't. Thus far I have made a (completely unnecessary) effort to keep both versions identical for numerical simplicity. However, after seeing a Rock Wren (#252 + 1) at Pt. Roberts on November 1st, my lists have once again diverged and will likely stay this way given the local rarity of this species. 

The main significance of this Rock Wren is that it was #250 for MEHA, the fourth person to join the 2015 250 Club. And so I would like to extend a big congratulations to someone who has greatly facilitated the rapid exchange of rare bird alerts and contributed immensely to everyone's Big Years. 

#252 + 1. Rock Wren. November 1, 2015. Pt. Roberts, WA.

After seeing several Ancient Murrelets (#252 + 2) at Pt. Roberts on November 15, I still felt compelled to make an effort to see them in the eBird Metro Vancouver county. My efforts since have included a sea watch from the end of the Iona south jetty, which produced only Marbled Murrelets, and a walk-on sailing on the Tsawassen-Duke Pt. ferry, which produced Ancient Murrelets only on the Vancouver Island side of the sailing, as determined by plugging GPS coordinates into eBird. It has been a great deal of (completely unnecessary) effort for a semi-year bird. Life would be much easier if birders ignored the international border across Pt. Roberts just the same as these murrelets do. 

 Count update: 252 + 2 on Nov 15.

October Briefly

October passed quickly with limited gains. The waning daylight impeded my birding before and after work, a whirlwind of rare birds outside Vancouver took my focus off the task at hand and field work took me out of town for a few days. Consequently, the effort I devoted to my Big Year was limited, as reflected by my piddly submission of only 13 eBird checklists from 9 days. However, there were two notable additions to the list.

A Clark's Grebe, which as rare birds always do, showed up while I was out of town. Fortunately it remained in the area for a couple weeks, swimming back and forth between the White Rock pier and offshore waters of Semiahmoo Bay. On some days it would thrill observers with close up views, while on others it was likely unresolvable among the distant flotilla of Western Grebes. I caught him somewhere in between.

#251 - Clark's Grebe - 9 October 2015 - White Rock Pier. The Clark's Grebe is on the right, with a Western Grebe on the left. With some stretch of imagination you may be able to see paler flanks and a narrower black stripe down the hind neck of the Clark's. And if you stare long enough, you may even be able to convince yourself that it has white lores. 

On October 12th a Tropical Kingbird was photographed along the Richmond West Dyke. Although this species has become of increasingly regular occurrence in recent years, it still remains an extremely rare bird for the area. According to the eFauna Checklist of Rare Birds of the Vancouver Area, there were only 3 records prior to 2008. This bird represents at least the 5th record since then, of which I've now gone 5/5.

#252 - Tropical Kingbird - 13 October 2015 -  Richmond West Dyke at Steveston Hwy.

But to balance these successes there was also great sorrow, the likes of which is known by few: on October 16 I missed a Blue-gray Gnatcatcher found by KELO at Boundary Bay. It was successfully twitched by several first responders¹, however, being the responsible employee that I am, I remained at the office until the afternoon by which point the gnatcatcher was never to be seen again.²

Two other birders joined the "2015 250 Club" in October and deserve special commendation: MITO on Oct 4 and ROLY on Oct 27. Well done both of you!

Count update: 252 as of Oct 31.

Footnotes:
¹Apparently I also missed quite a celebratory dance which I would have liked to see almost as much as the gnatcatcher.
²Despite blogging in anonymity, my blog has been discovered by some co-workers leading to suspicions about my priorities. Surely this sacrifice will alleviate all such concerns.

250



As of September 25, Phase 1 of the Big Year is complete. A Ruff at Boundary Bay was the big milestone bird. Unfortunately, 250 was reached early enough in the year that there remains considerable opportunity for the list to grow. I say "unfortunately" because this means that instead of sitting back with a cold glass of water and relaxing for the rest of the year, I now have to initiate Phase 2: 260-something. Below is a photographic recap of the recent year birds that haven't been featured on my blog

#250 - Ruff - 25 Sep 2015 - Boundary Bay. The Ruff is on the far right end of the island, and an American Golden-Plover is third from the left end.

#249 - Clay-colored Sparrow - 22 Sep 2015 - Stanley Park Rose Garden.

#248 - Sharp-tailed Sandpiper - 22 Sep 2015 - Reifel Bird Sanctuary. 

#246 - Vesper Sparrow - 8 Sep 2015 - Colony Farm.

#243 - Horned Lark - 6 Sep 2015 - Iona Island. Photo taken at the Tsawassen Ferry Jetty on Sep 17, 2015. 

As a tribute to the action-packed fall of shore birding at Boundary Bay, I would like to welcome you to the Boundary Bay Shorebird Simulator. Can you find the Bar-tailed Godwit? And if you're really bored, look for a Red Knot.

New Nemesis Bird

Move over Ruddy Turnstone, there’s a new nemesis bird in town: Red-naped Sapsucker. I spent 9.5 hours over four days looking for three separate Red-naped Sapsuckers during the last week! This species occurs rarely in Vancouver during spring migration, with one or two reported most years. They are reported even less often in the fall, and each repeated opportunity to look for one was highly unexpected. I will again present select excerpts from my Birder’s Diary to tell this grand tale.

Monday, September 14: I am forwarded photos of a “mystery” sapsucker from a private residence in North Vancouver. Though certainly a Red-naped/Yellow-bellied-type, which, or whether a hybrid, cannot be ascertained. I am told I will be informed if it reappears.

Tuesday, September 15: The mystery sapsucker is not seen by the homeowner.

Checking all sapsuckers carefully. (This Red-breasted Sapsucker was found dead on the side of a Douglas fir trunk. It appeared to have gotten its bill stuck in the tree and unable to dislodge it. A very horrible and unlikely fate. Photo: 22 Sep 2015, Stanley Park.) 

Wednesday, September 16: Just as I arrive at Iona in the evening to pursue a reported Brewer’s Sparrow, I receive a phone call alerting me that the mystery sapsucker is back, well photographed and looking very much like a hatch year female Red-naped! The better news still is that the homeowner is willing to let me and a couple crazies come try for it. I consider driving to North Vancouver then, but that would put me through some of the city’s most congested traffic during peak rush hour and would also require abandoning the Brewer’s Sparrow without even looking. Both birds represent good year birds, but I have never seen Brewer’s Sparrow in Vancouver, whereas I have seen Red-naped Sapsucker, so I opt to stay at Iona. No Brewer’s.

Thursday, September 17: Today is a day off work on account of the presence of rare birds. I feel that arriving at the sapsucker property early in the morning is an imposition on the homeowner, so I return to Iona for a second unsuccessful attempt at the Brewer’s Sparrow. We arrive in North Van at mid-day, learn the sapsucker was present earlier in the morning, and wait for 4 hours for its reappearance, which never happens. We leave the property with a new qualifier added to the competition, which is now officially a “No Backyard Birds Big Year”.

Friday, September 18: Half an hour after I finish my pre-work routine (a lap around Queen Elizabeth Park) and arrive at the office, a Red-naped Sapsucker is found at the park. Ouch! Despite receiving news of this bird very promptly, I am unable to find time to twitch it during working hours. I search for two hours after work with MEHA’s help but we are unable to relocate it.  

Saturday, September 19: I spend three hours in the non-stop rain at QE this morning. It seems as if the inclement weather kept many of the migrants present yesterday from leaving; about the same number of thrushes feast on berries by the duck pond, and a mixed flock of similar composition to the day before is moving along the slope of the quarry gardens. But alas, I do not find my sapsucker.  

Monday, September 21: To my disbelief I receive notice of another Red-naped Sapsucker, this one reported from Burnaby Mountain. Curses! For I am at the office without Beatrice (my car) to get me there. Fortunately, I have a very loyal big year support network, and MEHA comes to my rescue, picking me up from work and driving me to Burnaby Mountain with less than an hour of light remaining to find this ‘sucker. As I stick my head in to the foliage of the very first birch tree I find myself looking at the object of my despair. Final score: RNSA 3 vs ILPO 1. Only in the birding world does this translate to a winning score.   

#247. Red-naped Sapsucker. 21 Sep 2015. Burnaby Mountain. Photo: Melissa H.