picture courtesy of steph_takes_photos on IG
Having sat down in the middle of wooded trail areas of Florida and having truly studied this creature, I have compiled many notes. This post is a brief explanation of what will cause a FL Scrub Jay to make an alarm call.
Any type of predator bird larger than the FL Scrub Jay will set off the alarm calls. There is usually at least one Scrub Jay looking in the sky for potential threats at all times. They often see the threat well before I do. A large predator bird like a falcon or hawk will make them activate one of their more extreme alarm calls which is 5 or 6 shrieks in a row, sometimes even being made as they dive into bushes for cover.
Sometimes this can be a false alarm if the bird turns out to be a vulture. A vulture is a large bird and it looks menacing but is a scavenger and does not actively hunt in most cases. If Scrub Jays are around a vulture in close proximity they usually pay it no mind. Sometimes from a distance they cannot tell what type of bird it is and will give a false alarm. It’s better to be safe than sorry.
Anytime a dog is that far back in the trail it is with a human. Dumb humans let their dogs off-leash even where there are signs posted that it is against the law for them to do so. Dogs will attack and kill Scrub Jays. I have seen a dead bird left behind. The birds know it and will often let out 3 or 4 strong alarm calls to alert the group. For this threat they stay higher off the ground.
Larger cats like Bobcats will cause the birds at alarm. They will also follow it until it leaves the general area. Small cats (domestic felines) will also cause the birds to alert. But the small cats are good at staying hidden which is why they are very able (and willing) to kill birds. Having outdoor cats anywhere near a Scrub Jay habitat is a death sentence for Scrub Jays and in my opinion should be outlawed.
If Scrub Jays from another group trespass then you will get a few alarm calls and usually instant chasing action. The female will make her clucking noise when she spots a stranger male.