The Martians in Weinbaum's stories look somewhat like cartoon birds. Assuming continued human contact with them, sooner or later they will probably be shown such cartoons. Weinbaum died in 1936,so assuming that the film industry didn't change enormously from our time line it seems plausible that four iconic birdlike cartoon characters will exist. Donald Duck (1934) and Daffy Duck (1937) are almost certainly around, but they're the least like the Martians. Woody Woodpecker (1940) has the right general shape and sharp beak, but he spends most of his time in trees, which are uncommon on Mars. Finally, the Road Runner (1948) is the most like the Martians in many respects (except that he doesn't make many 100-foot leaps), and lives in a desert - Weinbaum's Mars doesn't have many mountains or cliffs, but the sand is a good start.
Assuming the Martians are exposed to cartoons would they prefer:
Road Runner (1948)
Woody Woodpecker (1940)
Daffy Duck (1937)
Donald Duck (1934)
Some other cartoon bird of the 1930s-40s I will name in comments
Their attitude to such a bird will be:
Mild derision (they think it's silly but fun)
Emulation (they will want to try his/her stunts)
If they ever meet a real bird of the species depicted they will be:
Some other emotion explained in comments
Click!! Cluck!! Cluck!!
If the animation process is ever explained they will:
Want to work for Disney etc.
Start their own movie industry
Declare a jihad on the human race
Not be surprised
Show some other emotional response explained in comments
Refuse to believe it.