I used to take smoke-breaks outside the hospital. Since smokers could only go to one spot, and smoking is done right after eating, it was a favorite spot for the local sparrows too. Being a soft touch, I took to taking stale ends to loaves of bread with me to feed them. If you look carefully, they are different.
By day three, the same birds had trained me that I "needed" to bring bread every day. Roughly 50 birds, and yet the same three landed first.
Is that a bird trick like Dan's kind?