Up until last year, Rex was a dangerous, feral dog.

After he was rescued by California man Ed Gernon, Rex calmed down and settled into domestic life.

So settled did he become, Rex even rescued an animal himself - a hummingbird that had fallen from a tree and was close to death near Gernon's home in Whittier.

Now the two are inseparable, mostly because 'Hummer', as she is known, refuses to leave Rex's side, even going as far as to share a water bowl with him.

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Inseparable: Rex, a rescue dog, managed to pay it forward when he found 'Hummer' close to death while out on a walk with his owner in Whittier, California. Now the dog and the bird are inseparable

Best pals: Hummer is constantly circling around Rex, who does not seem to mind the attention

All better: Gernon nursed Hummer - who was close to death, back to health, hand-feeding her a sugar syrup

'It was this little creature,' Gernon told CBS LA, adding that he believed the bird was dead because it was covered in ants.

'This fragile creature that the whole world wanted to kill and (Rex) was trying to protect her, so I thought I'd go the distance.'

Gernon nursed Hummer back to health, hand-feeding her a sugar syrup he made, and now she is an important part of the household.

'Wherever he was, she wanted to be close by,' Gernon wrote on a YouTube video of the two.

'She even started bathing in his water bowl, killing time while he ate before she'd start playing with him again. So strange, but amazing.'

Sharing is caring: The dog and the bird have become so close that they even share a water bowl

However, all good things must end, and Gernon is aware that Hummer will not be with them for too much longer.