Head office, Rana Pratap Bagh, Delhi011 2721 1512+91 97116 99511

Science project idea

Gravity-fed bottle bird feeder that refills itself

Seeds fall under gravity to fill a small tray as birds eat them, so the feeder keeps itself topped up. It shows gravity and also helps garden birds in the hot summer.

Make it yourself8 numbered steps, the materials and the science, all free.Go to the stepsGet a ready-made kitReady-made models, kits and spare parts in the store under Best Out of Waste.Browse Best Out of WasteAsk on WhatsAppAsk the head office whether a model or kit for this idea is available.Send a message

What it shows

Seeds fall under gravity to fill a small tray as birds eat them, so the feeder keeps itself topped up. It shows gravity and also helps garden birds in the hot summer.

The science

Seeds are pulled down by gravity. The holes near the bottom let seed out only until the pile at the opening blocks it, because the seeds rest against each other at their natural slope. When a bird eats from the pile, more seeds slide down. The same idea works in a grain silo and in a sand timer.

Materials

Cost: under Rs 50. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.

  • A clean 1 litre plastic bottle with cap
  • A plastic plate or a tin lid as the tray
  • Two wooden spoons or two sticks as perches
  • Bird seed such as bajra or broken rice
  • Strong string to hang it
  • Tape

Safety

For this project: An adult must cut the openings in the bottle. Hang it where cats and children cannot reach.

Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.

All the safety rules

Step by step

8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.

  1. An adult cuts two small holes on opposite sides of the bottle about 4 cm above the base.

  2. Push the wooden spoons through the holes so the handles stick out as perches.

  3. Cut a hole in the base, a little larger than the seeds, near the perch for the seed to come out.

  4. Tape the plate under the holes to hold fallen seeds.

  5. Fill the bottle with seeds and screw on the cap.

  6. Tie string to the neck and hang the feeder in a shaded tree or balcony.

  7. Put a small bowl of water nearby.

  8. Count the birds and species for ten minutes each day and record them.

What you should see

Seeds slide down and refill the plate as birds eat; a tally chart shows which birds visit and when.

Viva questions

A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.

1What makes the seeds go down?

Gravity.

2Why does the seed stop flowing when the plate is full?

The pile blocks the hole and the seeds rest against each other.

3Why keep water nearby?

Birds also need water in hot weather.

4Why hang it high?

To keep birds safe from cats.

Free ebook: Viva Questions for Science Projects

Take it further

Compare how many birds come to millet, rice and sunflower seeds.

Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.

Free ebooks for this project

WhatsApp us