From the Contact Station February 2024

A Little Ice with Your Winter Storm?

Christmas Bird Count:  Weather certainly has had a big influence on what we were seeing on the Refuge at the end of 2023 into January 2024.  On December 31, 2023, the Refuge was covered by birders doing the Audubon Christmas Bird Count.  We accessed every field and wet area to count all the birds we could find.  RNWR is a big part of the Sauvie Island CBC circle, which itself covers Vancouver Lake Bottoms up to the Lewis River, and most of Sauvie Island, parts of Scappoose and the Columbia River between.  It looks like the Refuge counters found about 94 species (sightings are still under review).  Most expected duck species were found with Northern Pintail coming in at the top with about 2700 counted across the Refuge, American Wigeon was a close second with over 2200, followed by American Mallard and Northern Shoveler.

There were 41 sightings of Bald Eagles, with about a quarter of those being subadult.  This number is always a bit soft (i.e. probably high) as the eagles move around so much, it is hard to determine how many have been counted twice by different teams.   What is disappointing, no Refuge team found a Rough-legged Hawk this year.   Only one was picked up on the Oregon side of the count circle.  But this supports the general feeling that many species have been slow to come south for winter.  Or, in the case of the Black-necked Stilt, slow to move on to the south. The stilt caused considerable excitement in December but decided to depart or hide for the count.  Fortunately, one was sighted on Sauvie Island. Same one?  Hard to say.  There was a brief re-appearance in early January on the Refuge, but subsequent high water has probably moved it south or out toward the beaches.  Most unusual for the count was an Orange-crowned Warbler found on Bachelor Island and two Barn Swallows flying over River S.  Our teams had eleven sightings of Short-eared Owls between River S, the Hunt Zone, and Bachelor Island.  It is a nice-sized population.  One other species of note on Dec 31^st was Black Phoebe.  There were ten counted on the Refuge.  More on that in a bit.  If you are interested in our local circle count, results will be published in the Vancouver Audubon newsletter at the end of February. You can find it on their website.

Snow Bunting!  Mid-January brought us exciting news about the appearance of Snow Bunting.  It’s one of those birds with a high cuteness factor.  We don’t see them often.  The last appearance of this bird was on November 9, 2020, when one was spotted on the road within the Hunt Zone.  The only other recent documented appearance was in November of 2010. This year, it was hanging out around Swartz Lake between #12 and #13 on January 11 & 12.

Although, they dip down into the US during the winter, they tend to stay on the other side of the Cascades and across the Great Plains with a few in the most northern parts of the Washington Coast.  Snow Buntings are high arctic breeders, using rock formations to set up nests where the male feeds the female during incubation while she sits the egg constantly in the cold environment.  Based on Christmas Bird Counts, population size has decreased by more than 50% during the past four decades, suggesting a serious decline of the species.  Although more study is needed, this apparent change in population size may also be due to shifts in winter distribution, possibly resulting from climate change, and not to any overall population decline. Unfortunately, our Snow Buntings did not arrive early enough to be counted on our CBC.

A lesson from the Snow Bunting:  How to find exceptional birds on the refuge.  We tend to bunch up in some places to view species where they have been seen before.  But if you hang back to take the bigger view, you might be surprised by what you will see that others are missing, like our single Snow Bunting.

 

 

The Storm:  Moving on to the afternoon of Friday, January 12 when staff prepared the Refuge for a shutdown of the River ‘S’ due to the impending storm.  I was hoping for snow to start early that day so I could do a late drive around.  There is nothing so beautiful as the Refuge with a clean coating of snow.  But that didn’t happen so alas, like everyone else in Clark County and the greater Portland area, we went home via the grocery store and hoped for the best.  I suspect the Snow Bunting was not bothered by the weather, being used to cold, but probably sought shelter too.

A week and a day later, we finally had access to River S, at least a part of it.  On Monday, January 22, we were able to access the entire loop in the afternoon.  No more Snow Bunting but waiting for us on Swartz Lake was a flock of Horned Larks.  Whoa, what?  The last, and only other one e-bird documented sighting of Horned Larks on the Refuge was in late September 2015 and it was a single bird.  Horned Larks are easiest to find in eastern Washington where they find their preferred sparsely vegetated prairies, deserts, and agricultural lands.  They feed mainly on weeds and grass seeds.  Occasionally they will turn up at Steigerwald; they have been noted annually since 2019.  But these 23 individuals, at least five of which were young birds of the

year, were having a grand time on the still-frozen Swartz Lake with group forays to the road, picking seeds.  We all heard, and some experienced, the strong winds coming through the gorge during the storm of the preceding week.  These birds were probably carried on those winds all the way to us.

Lakes freezing, snow covering fields, and temperatures dropping into the mid-teens.  How do the animals, or specifically birds, survive these conditions?  I turned to my book, Ornithology, by Frank Gill. When cold, a bird begins to tense muscles, usually the pectoralis muscles, and begins to shiver to increase oxygen production and heat.  Birds adapt to the average environmental temperature in which they live. Those living in colder northern climates only start to shiver at lower air temperatures than species of warmer southern climates. Snow Buntings do not shiver until air temperatures drop below 50°F, its lower critical temperature (LCT).  The LCT of large birds is lower than that of small birds, much like mammals where brown adipose tissue plays a role in heat production.  Birds acclimatize in winter, so they can maintain their body temperature for many more hours than in summer. Increasing their metabolic rates and short-term heat production help birds withstand winter cold stress.

Birds also select micro-climates, small spaces where weather conditions differ from the general climate, to reduce their heat loss. They will roost in holes or protected areas of evergreens; some may burrow into snow to find insulating protection. Birds will huddle together in a small tree hollow, moving around within a pile to find a warmer spot.  Some birds use facultative hypothermia to help them through cold nights.  Our Black-capped Chickadee can lower its body temperature by 6°C (about 11°F), and sometimes more, becoming mildly hypothermic.  Our local flock of five was quick to make it to the feeders as soon as we filled them. Getting that energy supply they needed.  Our hummingbirds go into torpor, a more extreme hypothermia, where they are incapable of normal activities. These are all energy saving measures which help birds live through stressful cold conditions.  Molting into fresh feathers in preparation for winter increases insulation.  These are amazing creatures that have developed ways to sustain themselves in adverse weather.

So, some thoughts on Black Phoebe:  This is a bird that is used to less challenging climates, staying mostly to the south of us.  But, as I discussed in the February 2023, From the CS article, the Black Phoebe is becoming more numerous here, staying over winter and nesting on the Refuge, possibly expanding north.  But this last month was not prime weather for Black Phoebe.  Considering the discussion on bird acclimatization to its environment setting limits on its ability to adjust during severe weather events, do we still have our phoebes here?  A quick look at e-bird for January shows two were spotted on the 20^th.  The area canvased was considerably less than for the Christmas Bird Count, when we had ten, so it is hard to say whether we lost them or not.  I know this is one bird I will be searching for as winter continues.  Roger did not find them on his January 24^th weekly survey, and he knows where they should be.  We will have to see if they have it in them to adjust to their new normal.

Snow melted quickly off the fields.  Our nutria were walking and sliding over the ice covered ponds, and trying to find better footing in grassy furrows as they were looking for green grasses to munch.  Similarly, Great Blue Herons were standing out in fields and along dikes, searching for food in the exposed grasses.   Birds seem to be slowly coming back onto the auto tour post storm.  All ponds are now ice free and with minor exceptions, all piles of snow have disappeared.   I am looking forward to a more normal winter population and am still hoping to get my first Rough-legged Hawk of the season. Or, who knows what other surprises will show up?

-Susan Setterberg, Ridgefield National Wildlife Refuge Contact Station Volunteer