Bindi Irwin has shared her sonogram in an update about her unborn child, who she says is now ''the size of a hummingbird''.

The 22-year-old conservationist - who is the daughter of the late Crocodile Hunter, Steve Irwin - is expecting her first child with her husband Chandler Powell and took to Instagram over the weekend to give an update on her pregnancy.

Bindi also gushed that they ''can't wait'' to start teaching their little ''Baby Wildlife Warrior'' about the importance of protecting the planet and ''the beauty of wildlife''.

Alongside a snap of the pair holding the baby scan and a koala, Bindi wrote: ''The animal joeys we care for are excited to meet our human joey. Baby Wildlife Warrior is about about the size of a hummingbird now! We can't wait to teach our little one about the importance of protecting our planet and the beauty of the wildlife and wild places we love so much. Thank you for your kindness and support on this magical journey. (sic)''

The pair announced their pregnancy news five months after they got married at her family's Australia Zoo in March.

Bindi posted a photo of her and Chandler, 23, holding up a baby sized version of their Australia Zoo outfits.

She wrote: ''Baby Wildlife Warrior due 2021.

''Chandler and I are proud to announce that we're expecting! It's an honour to share this special moment in our lives with you. Though I'm still in my first trimester, we really want you to be part of our journey from the beginning of this new life chapter. We couldn't wait to share the news as this beautiful little being has become the most important part of our lives.

''Your support means the world to us. Please let me know your best advice and send good vibes & prayers to our little sweetheart. Love & light.''

Responding to his wife's post, Chandler wrote: ''You're going to be the best mother.''

The couple tied the knot on March 25 at the Australia Zoo, which is where the couple first met.