Waiting for the crows to arrive. That’s Melinda Green of San Francisco who feeds #crows from her apartment window...and they reciprocate. #abc7now pic.twitter.com/VmKyxXB6b1 — Wayne Freedman (@WayneFreedman) September 2, 2019

Two of Melinda’s hungry crows right there. Food is just beneath the window. “We have established rules,” says Melinda. They know they need to come directly to the window,” she said. “When the blinds open, they know.” #abc7nkw pic.twitter.com/B1g94ANKir — Wayne Freedman (@WayneFreedman) September 2, 2019

Gifts left by crows are seen at a San Francisco woman's apartment on Monday, Sept. 2, 2019. KGO-TV

SAN FRANCISCO (KGO) -- When we think of life in San Francisco's Marina District, we conjure people, pets, joggers. But nature? Not so much, until we look above at who might be peering back down."So we have rules established," said Melinda Green. She's a retired computer programmer who spends considerable time at her apartment window or on her couch, looking out that window, waiting for her daily visitors."Caw, Caw," she vocalized. To a human ear, at least, the call sounds authentic."Did you work on that?" we asked."I did," she answered.We're three years into Green's relationships with two separate families of crows. They have come to learn when the blinds open, they'll find treats on the landing of her fire escape and on the windowsill.When we asked, "Did you train them or is it the other way around?"She said, "It's mutual."So maybe you're wondering what's the big deal about this. Plenty of people feed birds. But how often do the birds reciprocate?"The first thing was the top of a champagne bottle," Green showed us. Next the birds left assorted rocks, gummy bears, bones. Crows have been known to show this behavior before."You're not imagining things?" we asked."No," she said. "At this point I am sure they are gifts. They're showing appreciation for the food."How else could Green explain a piece of antique electronics that looks similar to a small key? Green found it in the very same place where she puts the treats."Do you feel honored?" we asked."I do," she said.Who wouldn't? Proof again of how when we give, we tend to get back ten-fold.One woman, in an apartment, in the city -- coexisting."What do they add to your life?" we asked."They're friends," she said.