Trump's interior secretary Ryan Zinke rode horse Tonto to his first day of work in Washington

On his first day on the job America's new Secretary of the Interior Ryan Zinke rode a horse to work down the streets of Washington DC.

Zinke, formerly a Congressional House representative for Montana, was sworn in to his new job heading the US Department of the Interior on Wednesday. He is charged with managing and conserving over 640 million acres of land owned by the US federal government, be it parks or natural resources including oil, minerals, and water.

Zinke made his entrance at the department's building on a horse named Tonto after a brief jaunt through the streets of the Capitol. He is the latest addition to US President Donald Trump's cabinet.

Zinke is a former military commander with a background in geology. As a Montana Congressman he served on the sub committees for federal lands and energy and mineral resources. Environmental groups have said he supported harmful, anti-wildlife legislation. However, in November he also carried through a bill to establish water rights on the Blackfeet Reservation in his state.

The issue over federal land is most prominent in the western states, such as Montana and Oregon, since roughly half of the total land there is owned by the federal government. Much of this has to do with the fact that most large national parks are in the western US. In the rest of America just 4% of the land is government owned.

Zinke pledged to "get to work" immediately and said he knows he'll "be held accountable to get things done". He wrote on Twitter that he was "humbled by the warm welcome at @Interior this morning." He has also praised his new boss as a "great president and a commander in chief I will
fight with."

Sen. Maria Cantwell (D-WA), the top Democrat on the Senate Energy and Natural Resources Committee, said she is not convinced that Zinke will be able to "stand up" to Trump and prevent oil, gas and mining companies from unduly exploiting public lands.

Senate Minority Leader Chuck Schumer (D-NY) has said that Zinke raises "concern" for "every lover of our great and grand national parks".

However Zinke has pledged to tackle an estimated $12bn (£9.7m) backlog in maintenance and repair at national parks and stand firm against attempts to sell, give away or transfer federal lands.