Policeman Bluejay or Babes in Birdland is a children's novel written by L. Frank Baum and illustrated by Maginel Wright Enright. First published in 1907, Jack Snow considered it one of the best of Baum's works.

In 1906 Baum wrote, and his publisher Reilly & Britton published, a set of six tales for young children, called The Twinkle Tales after their little-girl protagonist. The six were issued in separate chapbooks, but later collected into a volume titled Twinkle and Chubbins: Their Astonishing Adventures in Nature-Fairyland. The series was a hit; Reilly & Britton sold 40,000 copies of the little books in a short time. Such commercial success justified a sequel: Baum took his Policeman Bluejay character from the Twinkle Tale "Bandit Jim Crow" and cast him in a separate novel, to be issued the following year.

Baum published many works – adventure stories, melodramas, and juvenile novels — under pseudonyms; early experience had taught him that he ended up "competing with himself" if he released too much material under his own name. Both The Twinkle Tales and Policeman Bluejay were printed under the pen name "Laura Bancroft" — the only Baum fantasy works published under a pseudonym. Tongue-in-cheek, Katharine Rogers has called Policeman Bluejay "her best work...." Oz author and "Royal Historian" Jack Snow thought Policeman Bluejay Baum's finest fantasy apart from the Oz books.

Policeman Bluejay was another success for Baum and his publishers; a second edition appeared in 1911, under the alternative title Babes in Birdland. The third edition of 1917, also under the new title, dropped the pseudonym and acknowledged Baum's authorship. The book was issued in a facsimile edition in 1981, and was printed again in the second issue of the annual Oz-story Magazine in 1996. A volume that combined all the "Bancroft" material appeared in 2005.

Maginel Wright Enright was in her mid-twenties, and still near the start of her artistic career, when she created the illustrations for The Twinkle Tales and Policeman Bluejay. Her pictures for the "Bancroft" books have been described as having "a child-like grace, a clear clean outline, and a sometimes highly refined decorative sense."

The "Bancroft" works of 1906 and 1907 are united by a general concept: kindness to animals rather than cruelty. Baum recalled from his own childhood, and observed in his own sons, how harsh children can be to vulnerable animals. Baum wrote a preface to Policeman Bluejay that expressed this goal unambiguously; he noted that along with the "amusement" the story provides, he hoped it would inspire "a little tenderness for the helpless animals and birds" his young readers encountered in their lives.

This goal motivated the most extreme element in Policeman Bluejay — the hunting scene in Chapter IX, "The Destroyers," an extraordinarily violent scene in a story designed for young children.

At the story's start, Twinkle and Chubbins are lost in a "great forest." They encounter a "tuxix" — a creature that looks like a spiny turtle, but is in reality "a magician, a sorcerer, a wizard, and a witch all rolled into one...and you can imagine what a dreadful thing that would be." The evil tuxix casts a spell on the children, transforming them into little bird-like beings, with their own heads but the bodies of skylarks. (They resemble the human-headed, bird-bodied sirins, alkonosts, and gamayuns of Russian folklore.) Policeman Bluejay, the force of order in the avian world of the forest, leads the two child-larks on a flight through the sky; he esconces them in an abandoned thrush's nest in a maple tree, and with the help of a friendly eagle he retrieves their picnic basket (so that they don't have to eat bugs, worms, and grubs).