SAN FRANCISCO — Almost all creatures, great and small, are welcome in the city of St. Francis, patron saint of animals, whose spirit imbues this place with a love and regard for our nonhuman friends. Take just one example gleaned from census and city data: Dogs outnumber children here, making already assertive dog owners an even more formidable political force.

But the emergence in recent years of coyotes in the city’s parks, and sometimes in its expensive backyards and picturesque streets, has raised doubts about whether that founding legacy can survive. Will the two animal worlds — the domesticated and the wild — be able to coexist? Might they even, as many in this liberal city hope, ultimately complement each other?

Taking no chances, city officials recently cordoned off trails and barricaded a restroom in an area of Golden Gate Park where reports of coyotes following dog owners and approaching unleashed dogs have been rising. The coyotes are believed to be protecting their den and newborns during the pup-rearing season, which lasts from April through August.

“Coyote alert” signboards and posters, as well as those warning dog owners to keep their pets on leash, have been put up in Golden Gate Park and other pockets where coyotes have been sighted.