Seeing the right things!

Jenny the goldfinch shifted from one wing to the other. She munched on the small seeds that formed a mount beside her, while her eyes were glued to the television that played in the human’s home, where her parents had made a nesting place.

The room was all dark, and the nest which she was sitting in was well hidden behind the old refrigerator. The teenagers in the room lounged on the sofa, and watched television, and Jenny copied their style as she continued to watch the blur of colourful images that quickly flashed on the screen in succession.

Birds like Finches and Sparrows have an extra dimension to their vision: Ultraviolet(UV) vision! However, not all birds have this super power. Birds that can unlock this feature make use of two necessary adaptations: (1)Chemical changes in light-filtering pigments called carotenoids, (2) Tuning of light-sensitive proteins called opsins.
There are two types of light-sensitive cells, called photoreceptors, in the eye: rods and cones. Cone photoreceptors are responsible for color vision. While humans have blue, green, and red-sensitive cones only, birds have a fourth cone type which is either violet or UV-sensitive.

Birds acquire carotenoids (red/yellow/orange colouring pigments usually present in plants) through their diets and process them in a variety of ways to shift their light absorption toward longer or shorter wavelengths.

The blue-cone sensitivity is fine-tuned through a change in the chemical structure of these carotenoid pigments within the photoreceptor, allowing both violet and UV-sighted birds to maximize how many colors they can see. The sensitivity of the violet/UV cone and the blue cone in birds must move in sync to allow for optimum vision. The light sensitivity of opsins within the violet/UV cone is related to the mechanisms within the blue cone, which coordinate to ensure even UV vision.

This kind of visual sensitivity helps female birds discriminate very fine differences in the elaborate coloration of their suitors and choose the fittest mates, and also helps them search for hidden seeds, fruits, and other food items in the environment.

The dialogues of the actors on screen floated up to Jenny, who became more and more captivated with the drama. She couldn’t see as well as the other finches anymore, for she had been watching far too much TV for far too long! She flew a little closer and landed on the shelf in the room, and settled herself down, watching the characters play out an emotional scene.

“Fred, you’re the one! I know it!” said the heroine, collapsing in hysteria. “I know, Emma, but I must go”, said the tall, dark hero, leaving the heroine in tears. Jenny was in tears herself, and she hardly noticed her mother silently fly in and land right behind her. The shrill voice of her mother snapped her back into her senses.

“What do you think you’re doing?” screamed her mother. “Get back to the nest this instant!”Fumbling and stumbling, Jenny quickly went back to the nest and lay in a corner quietly, while her mother raged. “No responsibility at all! Do you realize you’re all grown up now, and you need to get out there in the real world? We still bring you food, but that’s not going to happen forever!

Do you even understand it’s past time for you to start your own family? Your friend Lisa’s even got a brood of her own chicks now! When are you going to get a move on and find a mate? But, no, all you do is watch that stupid colourful box like those idiotic, lazy humans! And today, you ventured as far as that shelf to watch that silly tele— televi— Oh, I don’t know what it’s called— that stupid thing! Why don’t you just get into that box then, and live there, why don’t you?” And Jenny’s mother gave her a few sharp pecks on her head.

“Mom, it’s called the television, for heaven’s sake”, said Jenny, flinching. “Get the name right.”“I don’t care what it’s called! It’s spoiling your life, that’s all I know!” cried her mother in anguish and fury. Just then, Jenny’s father flew in.

“And you!” Jenny’s mother turned on her husband furiously. “I told you a million times, Henry, that we shouldn’t build our nest here! And see what’s happened to our daughter!”

“Oh, she seems fine, as far as I can see”, said Henry absent-mindedly, and sank down in his favourite corner. “Fine? Fine? She’s addicted to that idiot box!” cried Jenny’s mother. “Her siblings are all gone, and have families and nests of their own, and this one is still here!” She gave another sharp peck on Jenny’s head.

“Oh, well. Send her out today to find a mate then”, said Henry, almost in a bored voice. Jenny felt too lazy to venture out. Besides, her favourite program on television would start soon. She kept her head under her wing, and pretended to be asleep.

“You’re not fooling me”, said her mother sharply, and gave her a push out of the nest. Jenny was forced to spread her wings and fly.

“Alright, alright”, grumbled Jenny. “I’ll try my best.”“And get some seeds too, while you’re at it”, called her father from inside, as she grumpily flew out of the house. As she came out, the bright sunlight almost blinded her.

It was too bright and she could hardly see anything! For a moment she considered flying back to the nest, but then decided against it. Her mother might get aggressive again, she thought. Her eyes took a while to adjust to the bright daylight after having spent months in the darkness of the house.

“I’ll just take her a few seeds that I can find”, she thought to herself. “By then she might forget the whole episode and be happy with the grains. And I can go back to watching TV.”

But fate had other plans for Jenny. As she went searching for seeds, she realized she couldn’t see all that well as before. She couldn’t spot the seeds from afar, or even the small fruits or berries. Her eyes blurred over. She decided to fly really low, so that she could spot the food. Things seemed better, but just before she could pick up the berries she had finally spotted, another goldfinch swooped down and made off with them!

“Ha ha… really slow aren’t you?” cried the other bird, laughing in glee. “You don’t seem very smart at all! Couldn’t you spot me coming from behind?”

Jenny didn’t know what to say. “I couldn’t”, she said quietly and turned away, though she felt quite angry that the other bird had taken away what she’d wanted.

But the finch didn’t stop talking to her. It looked like he had just noticed that Jenny was a female bird. “Hey, what’s your name? Where do you stay? I haven’t seen you around. Can we be friends?”

Jenny was quite annoyed with him. But then she remembered her mother’s warning to look for a mate. Jenny looked closely at him. He certainly seemed like a good potential mate. She could make out that he was a very handsome bird, but her eyes worried her again. She couldn’t see any bright colours on his plumage that set him apart. Everything seemed to blend in as one indistinctive blur.

“I’m Dave”, said the bird, gulping down the berries he had picked, without offering Jenny even one. “And yeah I can make out you’re quite impressed”— he struck a pose— “All the females are, actually”— he changed his pose— “But you seem quite different. You don’t seem very interested in fawning over me like the others.”

Little did poor Dave know that it was all because of Jenny’s poor eyesight! “I’ll be here again, tomorrow, same time! Think about it!” Dave flew away.

“Did he take away your berries? Here, have some”, said another voice behind Jenny. She turned to find another male finch, patiently waiting for her to accept the berries he was holding out to her. She took a few, and mumbled thanks. “I’m Gary”, said the bird confidently, yet without the cockiness of Dave. “See you around”, he said and flew away.

Jenny flew home, flustered and a little upset. Here was a wonderful chance to choose a mate, yet she couldn’t make out the better of the two because of her eyesight! She cried about it to her mother, who first scolded her for watching too much television and then laughed.

“Thank goodness our eyes are better than the humans’”, said her mother, handing her some red berries to eat. “Here, have these for a few days, and your special ultraviolet vision will be back. Then you’ll be able to decide who’s better.”

Sure enough, Jenny’s vision improved! The next time, when she met Dave and Gary, there was no doubt about it. She could now make out the subtle colour differences in the feathers of her suitors. Dave was of course, the more handsome, and healthier, than Gary. “I’m sure you’ll choose Dave!” said her mother joyfully. “You’re really lucky he likes you!”

But Jenny made a surprising choice. “Oh no, Mom, of course not. I choose Gary. Dave may be better looking, but Gary is a kind, good-natured finch. And I think that matters most of all.”

- Sneha Verghese is a research scholar in Journalism at Osmania University, Hyderabad. Also a post-graduate in biotechnology, she loves teaching and writing stories for kids to explain scientific concepts