Recent additions to our Winter avifauna. This (and some of the following pictures) were sent to me by Lise and Nat in Lanark County. -NC
“Decluttering” – the spousally mandated act of getting rid of/throwing out accumulating piles of important stuff, often deemed to be “junk” by the uninitiated.
“SNBU” – the AOU (American Ornithological Union) alpha code for SNow BUnting.
Covid stay-at-home expectations have resulted, in my household, in cleaning binges that all too often have taken the form of pressuring me to sort out my “piles” to determine what is important (and, therefore, saveable) and what is dispensable. So I had to come up with a measuring stick to determine what is important. Thus I began to sift through my aggregations of “papers” – printouts of PDF articles – with a view to “will I EVER read or need the information in this paper again?” The trouble is: you just never know…..somehow my wife seems to know…or thinks she does.
Anyway….in sorting through a series of filing boxes filled with file folders I came upon one titled “SNBU’s”. Obviously this was a keeper. But, in adhering to the process, I had to go through it article by article – this is a process that just can’t be rushed. I’m glad I did as it contained my old field notes from July 2004 when I was at Cape Vera on the northwest corner or Devon Island at a latitude of 78 degrees. The main purpose for being there was to help in a study of Northern Fulmars but I was able to use whatever down time this afforded to begin to study Snow Buntings. And I was amazed. What a bird!
Up until then they were simply a bird that appeared periodically in southern Ontario during periods of cold and snow. As soon as the snow was gone, so were they. At that point they were a birding “tick”. After my experience there they have been a preoccupation.
Despite the weather conditions – temperatures in the low single digits, a July snow storm, bitter winds blowing in off the polynya – the Cape Vera birds were thriving. The area met the two basic nesting requirements for this species: lots of good nesting sites and plentiful food. Numerous nests were located in the rocky scree at the base of the 300 metre cliffs (which were home to the fulmars) and under large boulders that had tumbled from the cliffs and rolled onto the flat rocky “table” between the cliff bottom and the sea. This table was notable for another reason: melting snow gathered in shallow pools, some large some small. The water, draining from the cliffs above, were laced with nutrients from fulmar droppings and these nutrients enriched the area around the ponds. They were ringed with rich green vegetation – a colour rarely seen in the high Arctic. This lushness also provided food for midges – Chironomids. These flying tiny insects look like mosquitoes but don’t bite. For many bird species they are important flying fuzzy meatballs.
Clutch of 5 eggs in a nest wedged down a small fissure in the rock.
Now, when I first arrived at Cape Vera the males were vociferously setting out territories and the females were busy finding appropriate sites and building nests. At that time I wondered what they could be eating as my searches around the ponds turned up only the very occasional spider and plant seeds were rare. This didn’t seem to deter them in the least. The nests I was able to find and access (access was the difficult part as they were often deep in the scree or under boulders not even a polar bear could overturn) contained, on average 5 eggs (range 3-7). But what were the parents going to feed their young? Occasional spiders wouldn’t come close to providing the nutrients that would be required.
Not to worry. As if on cue, hatching occurred at the very time when Chironomids began to emerge from the ponds. And I have never seen anything like it! They were everywhere, in huge numbers. And, when they first wander out of the ponds that have housed their egg and larval stages, they are slow moving and usually just sit beside the ponds, warming up – by the thousands….no, hundreds of thousands. This provided a feeding bonanza for parent birds wanting to grow their young.
Whenever I got a chance I tried to observe the food-gathering adults. The capture rate was amazing: On average they “pecked” (captured a midge…I’m assuming) at the rate of 1.6 pecks per second. Unfortunately I didn’t time the feeding length but if they fed for a minute – and had a 100% successful capture rate – then they would have obtained 96 midges. Two minutes at 100% efficiency would have garnered 193. The parent birds, when they had captured as many as they could carry, would take off, sporting black fuzzy moustaches, and head back to the nest to pass the feast on to their young.
As soon as parent arrives, moths open.
It has generally been reported that females make more provisioning trips to the nest than males. But I found that males averaged (between different nests) the same number: 8.57 per bird per hour, so just over 17 trips per hour per pair. One account stated that the birds might travel as much as 250 meters between food site and nest but I followed one bird that went 600 meters. Also, due to 24-hour sunlight, it is often assumed that the birds will forage throughout the whole day. Dr. David Hussell, who did a lot of his early work on Devon Island, suggested that the birds took a “break” of about 5-6 hours during the “night”. I found this to be the case as well: between 11 in the evening and 5 the next morning there was little to no feeding activity – it appeared that the female brooded the young and the male sequestered himself in a sheltered nook close to the nest.
So let’s do the math:
At 100% capture efficiency for one minute, the 2 parents, averaging 17 feeding visits per hour and keeping this up for 18 hours in a day, would provide their young with 29,610 midges. With an average clutch of 5 young this would translate into 5,922 insects per nestling per day.
If they captured prey at 100% efficiency for 2 minutes this would result in 11,909 midges per nestling per day.
If every “peck” did not result in a capture – let’s say they were successful 80% of the time – this would still work out to 4,738 midges per nestling per day for 1 minute of foraging time and 9,257 for 2-minute bouts.
Almost ready to get out into the world it’s been observing for the last few days.
It’s easy to see why Snow Buntings have evolved to accommodate Arctic conditions and a long migration: plentiful food! But with global climate change, what happens if a mismatch develops between the hatching of Snow Bunting young and Chironomid emergence? If the buntings had hatched just 5 days earlier they would have missed out on a huge proportion of this food source….occasional spiders just wouldn’t cut it. The timing was impeccable. For the sake of discussion, are their subtle cues that birds sense that cause them when to begin nesting/egg laying? Cues that coincide with the conditions necessary for the eventual Chironomid emergence?