The big blow, which started during the night of October 17th, was over; the violent SE winds, which at one point hit 60 knots, had subsided to 10-13 knots; and the 4-5 metre swell was flattening out. We were headed N in a big open stretch of the Gulf of St. Lawrence – if you put a dot in the middle of the ocean bordered by the east end of Anticosti Island, the west coast of Newfoundland and the north shore of Quebec….there we’d be. Out of the corner of my eye I noticed an UNPA (Unidentified Passerine) fly to the ship from the west and circle around to the back of it. When I took a break from the bridge I went to see if I could find it. Maybe it had taken a look and kept going….
I came upon it on the stern deck hopping around looking for something to eat amidst a number of heavy wire mesh bins holding equipment – a Blackpoll Warbler. Sadly, insects were few and far between after the big blow. Undaunted it kept searching. I returned to the bridge and never saw it again. Maybe it succumbed to starvation and hypothermia hidden away in the ships’ gear; maybe, finding no food, it kept going; and if it did, maybe it made it to land….or maybe it didn’t.
I’m not sure what paper(s) I got this from but I’ve read that around 80% of small songbirds don’t make it to their first birthday. 80%! I used to think that was terribly high. But, when you give it some thought, maybe it’s a miracle that it’s not higher. Take this little warbler. Let’s assume that it was a young one, hatched this past Summer in the boreal forest 200 km to the north (could have been more, could have been less). First of all, it would have to survive 12 or so days as an egg without a predator noticing its parents building a nest and then sitting on the eggs. Then it would have to survive another 12 or so days as a nestling, rapidly growing feathers to the point it could effectively thermoregulate and based on its parents ability to find the food necessary for this growth and deliver it furtively enough that the nest wasn’t detected. And then, upon leaving the nest, it would spend a week or so moving with the parents, being fed but also learning how to forage until the parents cut them loose to pursue their own destiny – complete moult of all feathers and then migration. At this point the young bird would also moult – but not completely, mostly body feathers and some wing coverts. And it would begin to move around the natal area (and beyond) – “disperse” – familiarizing itself with the area so that it would recognize “home” and identify some future possible nesting sites when it returned. And it would have to do all this while feeding itself and recognizing and avoiding predators. (At the dispersal stage, young birds are often clumsy fliers and an easy target for avian predators.)
So….lots of early hurdles but let’s assume that the bird makes it. Now the big challenge begins: it gets the urge for going, to make that epic flight from the boreal forest to the southern Maritimes/New England and then, flying NONSTOP across the Atlantic to South America. For this particular bird the first significant hurdle would be the crossing of the Gulf of St. Lawrence. For this bird to be where it was when I came upon it a number of explanations might be proferred: it started it’s crossing from the N shore the previous might, before the storm, and got blown backwards; it was making the crossing across Cabot Strait (between Newfoundland and Cape Breton) and got blown back to the NW. In both of these scenarios the bird found itself out over open water, running out of fuel, and the ship was an “island” that it sought refuge on. Another alternative was that it headed out when the storm started to abate – so a late morning take-off – landed on the ship for some respite and then took off again. This last option is a bit of a stretch if you consider that most songbirds fly at night. But it was getting late in the year and maybe the urge to go overcame the need to fly at night. Remember, I had seen a variety of songbirds a few days before heading across Chaleur Bay and I’ve seen warbler diurnal migration across the St. Lawrence in May at Tadoussac – diurnal migration in songbirds may be more common than we think.
Just for the heck of it, let’s imagine that this particular Blackpoll took off after a brief respite on the ship and carried on to the N shore of Nova Scotia. At this point it would have to find places to shelter and, especially, to feed, to recoup the significant energy it took to make the crossing in adverse conditions and to prepare for the flights to come. It would also have to be on the look-out for predators – accipiters move with migrating songbirds to take advantage of this flying buffet heading south.
Now the bird would have to make its way S to a place it could fatten quickly possibly changing the majority of its diet to berries (dogwood berries are particularly attractive as they have a relatively high lipid content). This would entail flights totalling several hundred more kilometers to get to the “jumping off place”. Here, after putting on a lot of fat, in many cases doubling its weight in about 2 weeks, the bird is ready and waiting for the “right” weather system, one that will provide assistance to lift its considerable bulk off the ground and push it SE until it meets up with the NE trade winds which will blow it over to South America – if the trade winds stopped for some reason the birds would simply keep flying SE until they ran out of fuel somewhere far out over the ocean.
I doubt very much that birds “feel” joy but after 80+ hours in the air over a hostile watery environment you might infer a feeling of, at least, relief…..It’s been a struggle but the bird has made it to its Winter home where it will have to find its way: identify food sources and recuperate, avoid predators, and simply get by until the urge for going in the Spring starts up.
Now, think of all those steps. There are so many things that could go wrong and impact the journey: predators along some parts of the route; contrary winds/weather systems – more so now with climate change variables; a poor growing season resulting in a lack of food for fattening; urban/suburban development limiting feeding and sheltering areas in the north; habitat loss limiting available territories in the wintering areas. And this is just half of the yearly cycle for this species.
Is it any wonder that 80% don’t make it back?