The 20 most popular reader's photos of 2019

short-eared owl
© Tony LePrieur / Flickr

From ancient trees and strange sea slugs to odd and adorable insects plus more, our most popular reader's photos of the year are a tribute to Mother Nature.

Readers submit nature photos to our Flickr pool and by email – and our readers are really talented. Photos come from all over the world and feature everything from the vast night sky to the minutiae of an insect's antennae. Each one is a wonder unto itself. While there are no bad ones, the following ten were extra great ... and earned the most views over the course of the year. Which one is your favorite?

Click on the image to read more about each photo.

20. Sea otter saves the day

sea otter eating purple urchin© Sam McMillan / Flickr

19. The Needles at sunset

needles rock formation© Rick Derevan / Flickr

8. Baby stick insect proves that Mother Nature is a mad genius (video)

baby stick insect© Andreas Kay / Flickr

17. Every circle is a tiny animal

tiny animals© John Turnbull / Flickr

16. Fuzzy bee sleeps in a flower

Bee sleeping in flower© marlin harms / Flickr

15. Pika gathers up the grass

American Pika© Tony LePrieur / Flickr

14. Pirate spider or alien, you decide

Pirate spider© Andreas Kay / Flickr

13. Beautiful ravens show off their smarts

three ravens© Tom Van den Bergh / Flickr

12, How are seashells formed?

Zebra winkle - Austrocochlea porcata© John Turnbull / Flickr

11, Why are cardinals so conspicuous?

cardinal© Richard Liebert / Flickr

10. White Mountains hold an ancient secret

white mountains© Rollie Rodriguez / Flickr

9. 170-year-old fig tree is a majestic beauty

8. Rainforest hoverfly has crazy moves (video)

hoverfly© Andreas Kay / Flickr
Read about the photo here.

7. See the tortoise beetle's adorable walk (video)

tortoise beetle© Andreas Kay / Flickr

6. Sideways glance, owl-style

short-eared owl© Tony LePrieur / Flickr

5. Meanwhile in Sweden...

Aurora© Josefine Karlsson / Flickr

4. Seagoing slug proves truth is stranger than fiction

Nudibranch© John Turnbull / Flickr

3. Spiny devil katydid is strange and adorable

Spiny devil© Andreas Kay / Flickr

2. Jackrabbit isn't a rabbit at all

Jackrabbit© Mark Heatherington / Flickr

1. This is what the world's oldest tree looks like

Bristlecone pine© Rollie Rodriguez / Flickr

Would you like to see your nature photo featured as the TreeHugger photo of the day? Join TreeHugger’s Reader Photo Pool on Flickr and add your pictures to the group. Alternatively, send it to with "photo of the day" in the subject line.