Eucalyptus signata is native to eastern Australia, and is one of many trees commonly known as Scribbly Gum. The habitat is dry eucalyptus forest or swampy areas at low altitude. Occurring from Morisset, New South Wales up the coast and ranges to beyond the Queensland border. The bark is typical of the scribbly gum, being blotchy white with scribbles, although most I saw had quite a yellow hue. White flowers form between July and September. The "scribbles" are caused by grubs that feed beneath the bark. This species is consumed by koalas, and is known as a "secondary" food source. By this, it means that the koalas have other tree preferences.
This spotting was on the Neembeeba Track in Blue Lake National Park, North Stradbroke Island. Exposed area with native vegetation, extreme winds (at times), salty air, and sandy soil. Full all-day exposure to the sun.
Eucalyptus racemosa is a similar species of Scribbly Gum, although, from what I can gather, it is more localised around the Sydney region of NSW.