The birch seed diet

[I find that right now I have two different strands that I want to write about. There are still stories left to tell from Tanzania, but here now in Maine it is deep winter, and that is both beautiful and timely. So I think I will oscillate between the two for the time being. Today, winter prevails.]

When snow is thick on the ground, food is scarce.  The Slate-eyed Junco, Junco hyemalis,  is a tiny bird, yet it somehow survives through the long hard Maine winter.


Some food sources are easy to see, like these apples rotting away on the tree:


Others are so tiny it is hard to imagine that they provide enough food even for a junco: this one is feeding away but on what?


A large area of snow beneath two gray birch trees was covered in what looked like wood-shavings:


These are the seeds of the birch tree, whose long slender catkin has blown down in the storm, and has been swiftly dismantled by the juncos:


Each seed is minute, with tiny wings, and two little antennae:


The gray birches growing a few yards down the stream have shorter fatter catkins,


and seeds with smaller wings (this seems to be a double-yolker!) :


They gobbled these up too.

The seed is about 2mm across, and 2000 seeds weigh about one gram. The amount of nutrition in these seeds is about 5 Kcal/g, and a junco needs 28 Kcalories per day to survive in the winter, so it needs to eat more than 5g of these minute seeds, or 10,000 seeds. Of course, its diet is varied, and other foods offer more calories, but you can see why it never stops eating. To get my 1500 Kcalories a day I would need to eat 300g of these seeds, or 600,000 seeds. I think I prefer good bread, good cheese, and a glass of red wine.


The calorie data on birch seeds is based on white birch seeds, and is taken from Grodziński, W., & Sawicka-Kapusta, K. (1970). Energy Values of Tree-Seeds Eaten by Small Mammals. Oikos, 21(1), 52-58. doi:10.2307/3543838

The calorie data on juncos is taken from Seibert, H. (1949). Differences between Migrant and Non-Migrant Birds in Food and Water Intake at Various Temperatures and Photoperiods. The Auk, 66(2), 128-153. doi:10.2307/4080440

I am responsible for the maths!

PS How to weigh a junco, from a 2020 article in Nature on the work of Pamela Yeh:

” A dark-eyed junco being weighed: “We have a digital scale,” says Pamela Yeh. “We’ve put a bird head-first in the cup, and it’s dark in there, so he doesn’t move very much.”



How the elephant masters its trunk 2: outreach

Apart from eating, trunks are good for a multitude of other things:



Making friends

Elephant Orphanage. They are returned to the wild whenever possible.

Wrestling matches:

Male elephants jousting, for fun.

And when you are all grown up they are good for protecting and corralling your baby:


The multipurpose trunk can also be used to make noise, loud noise! Here are three different types of trumpeting from the Elephant Voices website:

But the best trick of all is to use the trunk as a snorkel, to breathe underwater. This video shows what I mean:

There is an astonishing underwater video out there of a snorkeling Asian elephant in deep water in the Andaman sea, but it is part of a tourist show, so I am not confident that the elephant is being properly treated, and I have chosen not to link to that video.

According to Rudyard Kipling, this wonderful trunk is all the crocodile’s fault…



How the elephant masters its trunk 1: the basics

[This is my 200th post. I wonder when I will run out of natural wonders to share?]

Learning to use your trunk is tricky. Young elephants, like young children have to practice their fine motor skills.

Everybody knows that a trunk is an elongated flexible nose (it is actually the nose fused with the upper lip), and indeed if you look at it from underneath, the anatomy is quite clear, including the two nostrils, which go all the way up! And it can still be used to sniff out two sweaty tourists in their jeep.


To nurse, you have to get it out of the way, so your mouth can reach the teat:


But the trunk comes into its own when you need to reach the water at the bottom of a hole that your mother has dug deep in a dry sand river (an underground river):


You kneel down, suck up the water, then squirt it out of your trunk into your mouth. You can no more drink it through your trunk than we humans can sniff water up our noses and down our throats. Occasionally you get sand by mistake, but that’s fine if all you want to do is cool down:


The African (but not the Asian) elephant’s trunk has two flexible “fingers”, that can grasp things tightly:


As you get older, you become so dexterous that you can pick tiny leaves and flowers off almost bare spiny bushes:




Next time: It’s not just for eating and drinking.

P.S. For the technically minded amongst you, the elephant’s trunk, like our tongues and like octopus arms, is a muscular-hydrostat. (Kier and Smith 1985). It has no bones to keep it stiff. It is a cylinder of fixed volume, so to make it longer, you must make it thinner. It has longitudinal muscles, and transverse muscles, and bending it requires the use of both. So a baby elephant learning to use its trunk to pick leaves is a bit like a baby human learning to use its tongue to make speech sounds. 




Leopards Redux

[I hope you enjoyed your break from my blog posts, and the first 2020 posts’s 7000 mile detour back to Maine. I am not quite done with leopards, though. No self-discipline, really.]

This leopard in the Serengeti had two teenage cubs, and they were returning from hunting early one morning. She rubbed herself against an overhanging tree to scent-mark her territory, sniff another leopard’s scent, or maybe just scratch an itch:


Then she moved towards a large rock formation, where she had stashed the kill:


This shot gives a better sense of the rocky outcrops the leopards  favor; they are the perfect place from which to mount an ambush of an unwary passing prey animal:


And here is the mother again, posing like a 1930’s Hollywood starlet, except that this coat is truly hers :


A different leopard, but I couldn’t resist the Eartha Kitt vibe:


The IUCN classifies the leopard as Vulnerable, and the fur trade is one major threat to their survival. Apart from international buyers, local people use the skins as ceremonial garb, so a project is trying to encourage the use of synthetic furs instead, and seems to be having a surprising amount of success:

Still,  I yearn for the days when there was a balance between wildlife survival and local traditions, undistorted by the outside demand for skins.


A not-so-happy New Year: a hawk strikes

[This has to be done today, I feel, even though I am in the midst of an African series of posts. Normal service will resume soon. And Happy New Year! ]

On New Year’s Eve in Maine we were in the midst of a two day snowstorm that brought us 12 glorious inches of pristine snow for 2020. As soon as it ended, I went for a final snowshoe of 2019. There are old apple trees behind my barn,


with last fall’s fruit still hanging on the higher branches, and on the ground underneath.


These are a magnet to a variety of animals, like this deer who had walked by some time earlier, while the snow was still falling fast*:


Back to the tree: beneath the boughs I found the debris of a life and death struggle.  From a distance, here is what I saw.


It was a recent incident;  the snow had only tapered off in the past hour, and these crisp marks had been made after it stopped. The story begins with the round disturbance at the top right, then the drag marks, leading to the denouement at the bottom left.

This is a close-up of the top right: look at the circular wing marks.


A hawk* has dropped down from the tree onto some small victim, and in fact you can see where the bird disturbed the snow on the branch of the tree above, as she perched in wait:


Having grabbed her victim, there is a short tussle as she gets a good grip and drags it leftwards.

The mouse or vole would have been under the snow, and she would have located it by ear.  A single tiny smear of blood part-way along the drag marks was the only evidence of violence.


Then here is a close-up of the final left-most disturbance: she lifts the rodent up,  and takes off, mouse-tail dragging across the snow, and her wingtips just grazing the snow in the top left-hand corner.


One tiny mammal that never made it to 2020.

* I’m pretty sure the earlier pair of tracks are just deer tracks coming and going, at different speeds. The following morning 20 feet away I found fresh tracks with the gait pattern like the ones on the left in the earlier picture, with the same roughly 5 foot stride, and a clear deer imprint in the bottom of each:


**I can’t be sure what type of hawk this was. The hunting method is typical of a Broad-winged Hawk, but they don’t over-winter round here. Red-tailed Hawks and Cooper’s Hawks have both been seen in the general area this December, so it could have been one of these, but Cooper’s Hawks prefer small birds as prey. There’s a small chance that it was an owl, not a hawk.  Barred Owls overwinter in Maine, and occasionally hunt in the daytime.  If anyone can be more definitive, let me know.


%d bloggers like this: