Troubled Teens in the World of Swallows

Dear Jane and Other Nature Lovers,

Once again I return with a story of the wonders of one’s own backyard! I was headed out this week for a walk along the River, about to go through the back gate of my mobile home park  that borders the levee. Something made me turn around and look up.  I blinked my eyes with wonderment as my gaze took in a row of 31 swallows, perched at regular intervals along a telephone wire.

swallows lined up, evening
8 of the 31 Violet-green Swallows lined up on a telephone wire next to the San Lorenzo River, July 6, 2018, Photo by B. Riverwoman

Usually I find these summertime visitors swooping over the river at breakneck speeds,  rarely if ever pausing to rest or pose for a photo.. Now here they were all lined up for me to enjoy and study at my leisure. What was going on?  I lost no time – immediately snapping about 150 photos, without much idea of what I was recording!

Colors from back
Juvenile, Male Violet-green Swallow, El Rio Mobile Home Park, San Lorenzo River, July 7, 2018,  In spite of the telltale downiness, this juvenile must be pretty close to adulthood.  Photo by B. Riverwoman

Judging from all the fluffiness on the breasts and bellies of the birds, I figured out pretty quickly that almost all of the 31 birds were juveniles.   Only once did I glimpse a parent feeding a young one, somehow managing to capture this photo of a young one’s urgent hunger pangs.

 

violet green begging baby
Begging juvenile Violet-green Swallow.  El Rio Mobile Home Park, San Lorenzo River, July 9, 2018.  Photo by B. Riverwoman

Most of the perched birds were approximately adult size.  And looking more closely, I realized that most of them were some complex combination of brown, white, gray and black, with little sign of the vivid green backs and iridescent violet tails of the adult male, nor the duller violet and green of the female.

creamy gape 3
Female juvenile Violet-green Swallow, El Rio Mobile Home Park, next to San Lorenzo River, July 6, 2018.  Note downy undersides, creamy white gape, marbled marking over eye, lack of much green and violet color on back and wings, shorter primary wings.    Photo by B. Riverwoman
Juvenile male 2
Juvenile Male Violet-green Swallow, El Rio Mobile Home Park, next to San Lorenzo River, July 6, 2018.  Note green back and cap, clean white over eye suggesting a male.  Still downy, no visible gape., slightly longer  primaries.

When I got home, I checked BNA for the breeding schedule of Violet-green Swallows. It reported that on the West Coast, this species normally arrives in early May, lays its eggs sometime between mid-May and mid-June, that the eggs normally take 15 days to hatch, and that the babies then stay in the nest for an average of 27 days before they fledge.   Calculating quickly, I realized that this fit exactly with what I was seeing.  Our Violet-greens did arrive in early May and so might be expected to leave the nest sometime between July 1 and August 1.   And here they were, 31 adult-sized but still downy fledglings  on July 6, right on schedule.

According to BNA, before the young have fledged and are still cozily nestled in their nests,  they feast  on a protein-rich diet of insects, actually growing heavier than their parents.  Then, during their last week as nestlings,  their weight returns to roughly the same weight as the parents.  So this is what I was looking at ––  fledglings that were already adult sized but still showing the downiness of the nestling.

As I was watching them I was struck by the incessant activity of many of them.   itching 5I was lucky to run into Kitty Stein at a Bird Club event on the weekend and told her about all the babies. She is very active in the local Breeding Bird Survey and asked to visit the scene.  She helped me solve the problem of why they were incessantly preening. They weren’t preening. She suggested that they were probably  scratching themselves in order to relieve the itchiness caused by their pin feathers (new feathers) pushing through their skin – just like a human baby’s teething woes.  In addition, I learned from BNA, that the young birds are vulnerable to surface parasites,  adding to  their pin feather discomfort.

 

itching 3
Juvenile female Violet-green Swallow, El Rio Mobile Home Park, San Lorenzo River, July 9, 2018, Photo by B. Riverwoman

Another plausible explanation for their ‘preening’ behavior is that the juveniles were removing the waxy coating that sheathes their pin feathers, something that has to happen before the new feathers inside the wax can unfurl. But since the young ones had presumably managed to fly successfully to the telephone wire, we know that at least their wing feathers were already functioning pretty well. Still – there remained enough downiness on other parts of their bodies that they might have been removing wax on these breast feathers as well as scratching themselves.  So much for a teen-age swallow to deal with!

There were also some fledglings that were sitting without moving?  What about them?  BNA had an explanation for that as well.  It said that ‘sunbathing’ helps juveniles control the parasites by raising the temperature of the body to a point that seems to either drive away the parasites or kill them.  According to the BNA the juveniles can go into a trance while sunbathing and lose their balance. I saw that!  Here’s a juvenile I caught almost tipping off the wire, perhaps falling asleep and waking just in time to right herself.

Balancing Act
Juvenile Violet-green Swallow on the right regaining his (?) balance, skillfully using his growing primaries. El Rio Mobile Home Park, San Lorenzo River. July 6, 2018. Photo by B. Riverwoman

And below,  for comparison’s sake is a photo of an adult female Violet-green Swallow with some subtle brown marbling on its cheeks to distinguish it from the snowy-cheeked male, but with no down on its breast and belly.  Here, also,  you can see clearly the long primaries extending way past the end of the tail.

Long wings 2
Female Violet-green Swallow, El Rio Mobile Home Park, San Lorenzo River, July 9, 2018, Photo by B. Riverwoman

 

Honestly, I’m not 100% sure about any of the above identifications.  But I thought that if I stick my neck out and make my best guess, I may get back more info from readers.  Feel completely welcome to challenge me.

Changing subjects rather drastically, –  it was nice, wasn’t it, Jane, that Mark Dettle, the head of the Public Works Department, chose to notify both of us, as well as many other stakeholders, about the Department’s upcoming plans to begin their annual flood control work all along the river.  They know how concerned we get each year!  But it wasn’t at all nice to learn that they may be planning to push the beginning date even earlier than August 1. I know that you have been in touch with Mr. Dettle about this and I plan to send a letter tomorrow. I think we both agree that in order to protect breeding birds on the River, the beginning date should be August 15 at the earliest and preferably September 1. I know Public Works worries about early  rains and the availability of contractors.   They clearly have their own set of problems and do their best to make it all work. Hopefully the schedules of the rain gods, the contractors and the breeding birds can be coordinated.

Did readers see the article in the Sentinel on July 6 about the new City laws regarding sewage leakages into the San Lorenzo River? Some property owners are not going to like the required inspections and costs of fixing sewer pipes on their private property.  But the news made me happy and I think I speak as well for the birds.  There have been just too many reports of sewage leakage seriously contributing to the fecal bacteria count in the River.   We humans and the birds all drink out of the same river.  Click here to read the full story.

All happiness to birds and people!

Barbara

 

 

 

 

 

 

 

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