Monday, June 17, 2019

Migrant Pollinators In My Backyard.

A White Winged Dove sitting amongst some white blossoms on top of a Saguaro cactus.In support of National Pollinator Week, I’ve decided to showcase a pair of very welcome summer visitors to Southern Arizona, the White Winged Dove (Zenaida asiatica) and the Lesser Long-Nosed Bat (Leptonycteris yerbabuenae). These species have several things in common: they are super-pollinators, they migrate between southern Arizona and Mexico and they are both flying around in abundance in my neighborhood.

Although I have lived in the Sonoran desert for many years, I have to admit that I paid very little attention to the doves around me. I had heard their calls (they are hard to miss), but I attributed most of that to Mourning Doves without giving it much thought. All that changed a little over a month ago when I opened my bedroom curtain and came face-to-face with a bird sitting on a nest. It was so close to my window that I could have reached out and touched it. In order not to disturb it, I quickly and quietly closed the curtain. But, not before surreptitiously taking a photo. I showed the picture to a co-worker who excitedly said. “That’s a White Winged Dove! They are so cool!” I
2 white winged doves (an adult and a juvenile) sitting in a nest in the branches of a tree.
White Winged Dove Adult & Juvenile
wondered why and thus began my new-found fascination with this bird.

White Winged Doves appear in southern Arizona in late spring to begin their breeding season here. What makes them special is that they migrate at this time to correspond with the reproductive cycle of the iconic Saguaro cactus (Carnegeia gigantea). Saguaros begin flowering from late April until mid-June; fruiting and ripening take place in June and July. As soon as they get to town, White Winged Doves start visiting the saguaros. They hop from one cactus to another sipping nectar and picking at seeds until the fruit comes in and the feasting begins. It is this flitting to and fro that makes them exceptional pollinators as they fly with pollen all over them. The doves are also adept at dispersing seeds; they scatter them everywhere they go. Here is a video of them in action.

The White Winged Dove and the saguaro are a perfect example of Mutualism in nature. This is when two species depend on and benefit from each other. The doves rely nearly exclusively on the saguaro for water and nutrients and the cactus needs the birds to spread its seeds and pollen.

Thousands of bats in flight at sunset.
Lesser Long-nosed Bats travel at least 1,000 miles north from Mexico to join us here in southern Arizona for pretty much the same reasons as the dove: to have babies and take advantage of the cactus buffet. In response to the presence of these pollinators, the saguaros have generously adapted to provide for both day and night feeders. Not only do their flowers bloom at night and stay open until the afternoon of the following day, nectar is produced in the night and in the morning. There is clearly enough for everyone!

a close up of a Lesser Long-nosed Bat on a black background approaching a white cactus blossom.
Lesser Long-nosed Bat
Saguaro cacti are not the only form of succulent on the menu for Lesser Long-nosed Bats. They also feed on various types of agave. In fact, those people who love tequila (okay, maybe not the morning after) owe a debt of gratitude to these bats. Simply put, without bats pollinating agave in the natural manner, there would be no tequila. As the demand for more, and higher quality, tequila has increased the attention paid to these creatures has also increased. Once on the endangered list, these little guys have made a comeback in part due to those growers preserving safe migratory pathways for them. Nothing has proven to be as successful in getting a good crop as the old bat standby. Rarely does increased human demands bring back a species from the brink, but this seems to be the case here. Here is an interesting video with more on this.

Two White Winged Doves sitting close together with their heads resting on each other.
Dove Love
I spent weeks peeking at the bird family in my bedroom tree; it was as if I was in on a secret world. I learned that both parents take turns sitting on the nest and, although their markings are essentially the same, I came to recognize each individual. They laid two eggs, but only one survived. That baby was remarkably strong and beautiful and gifted (do I sound like a proud relative?) and was up and out in no time. Now all that is left in their spindly little nest is the left-behind unhatched egg. It seems sad now. White Winged Doves are monogamous, at least through a mating season, and sometimes reuse a nest, so I take a look everyday hoping they’ve come back. I wish I had a picture to share, but I was worried about disrupting them, so the only pictures I have are through screen and glass and the details are hard to see. However, this blog has some pictures that show just what I was seeing. If you like birds in general or just want to see some truly amazing bird pictures, check out these 2018 Audubon Society Award Winners.

Submitted by Pam

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