Competition, affairs, family drama… Are birds more like humans than we know? As the weather heats up so does life for the song sparrows. Read on to find out about the major changes happening in the population!
Now that it’s basically summer the temperatures are pretty bearable all day and throughout the night, but it is always wet! Even when it’s no longer raining- or when it’s early in the morning- the bushes hold a lot of moisture. While we’re out in the field I’m always wearing rain gear so it doesn’t matter… but now I’ve started gearing up just to walk the shrubby path to the outhouse. I’m sure you can imagine how frustrating it is gearing up in boots, overalls and a rain jacket just to take them all off a few seconds later?
Fieldwork
This week we set up nets and baited traps in territories of single males. Catching birds that are looking after a nest may cause them to abandon it. We caught a few song sparrows. Knowing their adult measurements helps us track growth. It can be pretty difficult to get their little legs out of the net once they have twisted themselves in it.
Crazy things are happening with the song sparrow couples- I don’t have TV on the island so this is the closest thing I’m getting to reality TV. This year the population (which has historically been as high as 70 on this little island) has crashed to 3. And now it could be down to 2. In ecology, population size is determined only by the number of females- take that patriarchy (haha)- no, it’s not that males aren’t important- rather, estimates of female abundance help us to understand the total number of individuals contributing to future generations. All three females laid 4 eggs a few weeks ago. We watched the chicks grow to independence and now it is around the time the females should be producing their next clutch. There is one superstar couple that made their second nest and has already laid 4 eggs… they’re so tiny.
Another female in the population decided to move her second nest over into the next territory over while her first partner continued to feed their kids from their first clutch… its exactly what it sounds like, she’s left her man to raise their kids while she runs off to start a new family with the neighbour. This could mean many things…. 1) the kids in her new nest are fathered by her new man. 2) the kids are fathered by her ex-man and he sneaks into the new man’s territory to feed them if he sense they are his. 3) the kids are fathered by her ex-man but adopted by her new man because she nested in his territory. Male birds will sometimes adopt and feed other male’s offspring. Alternatively, he may ignore her kids completely or even become abusive to them. My research advisor said one time he saw a new male beat the kids in his territory so much that the female would step in and defend them. Later he found one of the female kids from that clutch had grown up with a dent in her head. He said she was a very weird bird and never mated, which he hypothesized was due to her PTSD. I don’t know if that’s even possible… He often analyzes birds like they are humans, and the more time I spend around them, the more they remind me of us too!
As I said earlier, the population may be down to two and that’s because the third female has disappeared entirely. She is no longer with her original male, but we can’t find her anywhere else either. We found the feathers of one of her kids scattered over a barren rock, meaning he was the unlucky victim of a hawk attack. We’re not sure if she was snatched too
I started to find light blue eggshells- some nearly full eggs- littered around the trails. The explanation behind this is really neat. When eagles are on the move every bird on the island freaks out and leaves their usual spot, every bird except crows. The cormorant birds, which are usually stoic birds perched very still on a cliffside, abandon their nests and seek safety when the eagles come. This leaves their eggs unguarded at which point the sneaky crows come in, steal the eggs and leave the shells, and sometimes part of a fetus, all over the trails.
Have you ever not known that you’re scared of something until you face it? That’s what happened to me when I first saw tent caterpillars blanketing the shrubs around the island. They form a cluster the same size and colour of a sparrow- which is frustrating when I’m trying to find birds. A group from UBC came to the island to study the caterpillars for a day. They found over 500 nests.
There are also some gorgeous rose flowers blooming all over the island which sort of make up for this gross occurrence.
“We still do not know one thousandth of one percent of what nature has revealed to us”
-ALBERT EINSTEIN
Last Updated on May 18, 2023 by Megan Duchesne