A few osprey summer on the Pacific Northwest island where I live, and they will be arriving soon. I just love hearing their piercing chirps and to see them fishing in my local bays. I don’t know of any osprey nests on the islands, and while there are nests in western Washington I know of, I can’t get anywhere near close enough to see much of the action. So to get my fix of osprey nest watching, I follow the nest cam on the Whirley crane in San Francisco Bay in Richmond, California. The season there has just begun.
The pair of osprey who have made the Whirley crane their home have been named Richmond (after the city) and Rosie (after Rosie the Riveter: it was women who operated the Whirley crane). The crane was used to build and load Victory ships during World War II in the Kaiser shipyards of Richmond, for the war in the Pacific. It’s common for osprey to nest on human-made structures these days. There are far fewer suitable trees along shorelines in the modern era of widespread development. Human activity also draws in raccoons, which have a harder time climbing human-made towers than trees.
Rosie (on left) feeling broody a day before laying her first egg, Richmond (right) keeping watch
The cameras pointed at the nest allow online viewers to follow the action, and to get to know the birds in a way impossible in real life. Golden Gate Audubon Society has been documenting the activity over the years and saving photos and video. This crane has hosted pairs of ospreys since 2010. Richmond probably appeared first as the male of the 2016 season, and he has overwintered in the Bay Area since then. Rosie appeared in early spring 2017; she and Richmond have raised two or three ospreylings every year since. While Richmond occasionally shows up at the Whirley crane over the winter, Rosie flies down to winter in Mexico or Central America in mid-September, returning usually in late February.
This year is the pair’s sixth nesting season together.
Once Rosie returns, the pair renews their bond. One year Rosie was a bit late and a female floater was planning to move in until Rosie finally showed up and drove her away. Richmond was like, Well, where were you?? But seriously, they seem very devoted and know each other well.
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Nest-construction
For a week or so after she arrives Rosie spends time fishing and fattening up, regaining her strength after her migration. Then the pair turn their attention to refurbishing their nest.
Ospreys have a well-defined division of labor when building a nest. The male collects nesting material while the female lays out the material the male brings. The female distributes and shapes the nest. She rarely helps bring nesting material. avianreport.com/...
They got a late start laying eggs this year partly due to a nest more trashed than usual. Some of that was undoubtedly winter storms but in February a pair of nearby ravens used all the good sticks from it for their nest before Rosie arrived late in the month and Richmond didn’t make much effort to drive them away.
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By the end of March though, the ospreys really picked up the pace and got the nest in good shape.
Richmond brings a toy
Richmond takes his responsibility of bringing resource material very seriously. He’s pretty creative about it too. Sometimes a bit goofy. Since this nest is in a major urban area, there’s a lot of human detritus Richmond hauls in, like stuffed animals, umbrellas, jackets, tarps, fleece blankies, packing material, hats. Even roadkill, like the flattened skunk he brought in one time. Usually Rosie looks at these items askance and throws them overboard, though sometimes they last for weeks. The Audubon people can climb up there and will remove hazardous items, like strapping tape and rope. This year I’ve seen a disposable mask in the nest already, ugh.
In 2017 Richmond brought in a big heavy branch and during all the subsequent maneuvering and unbalanced walking around in the nest, one egg was broken. So it’s possible to take this collecting drive too far.
Later in the season, Richmond’s offerings may be more for entertainment than for nest-building.
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Mating and Egg-laying
This year’s eggs are later than typical but not significantly so according to the records. Rosie laid their first egg on Tuesday, April 5 this year.
First egg data:
2017: Apr1; 2018: Mar31; 2019: Mar31; 2020: Mar30; 2021: Mar24; 2022: Apr5
Science sources (such as Henry L. Ferguson Museum Natural History) report anywhere from 1-3 days from when one egg is laid to the next; for Rosie it’s about three days between eggs. Soon after she lays an egg they mate again. In birds who have more than one egg in a clutch, each egg is fertilized separately and goes through development before the next one starts. All About Birds summarizes the sequence of development:
An egg’s story begins in a female bird’s single ovary. When an ovum is released into the oviduct and fertilized, it is just a protein-packed yolk. The albumen—the gelatinous egg white—is added next. The blobby mass then gets plumped up with water and encased in soft, stretchy membrane layers. The first globs of the calcium carbonate shell are then deposited on the exterior, with the mineral squirting from special cells lining the shell gland (uterus). Pigmentation, if any, comes next, with an overall protein coating added before the egg is laid. It takes about 24 hours to build a single egg.
In his book, The Most Perfect Thing: Inside (and Outside) a Bird’s Egg, University of Sheffield zoologist Tim Birkhead compares the pigmentation process to an array of “paint guns.” Each gun is genetically programmed to fire at a certain time so that the signature background color and spotting of a species’ eggs is produced.
From giddy thing’s Dawn Chorus about a first-hand osprey rescue: Dawn Chorus: Adventures with Ospreys
Despite the variety of egg colors and patterns, the palette is surprisingly small. Egg pigments are versatile substances made of complex molecules synthesized in a bird’s shell gland. Only two pigments are at work. Protoporphyrin produces reddish-brown colors. Biliverdin produces shades of blue and green. More of one pigment, less of the other, and the egg gets a different background color, spots of a different color, or a combination of both.
www.allaboutbirds.org/...
Egg-laying and then mating after the second egg on Friday afternoon, April 8, laid three days after Egg #1, as is typical for Rosie:
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The nest monitors at the SF Bay osprey cam site answer questions in the chat room. For example some viewers were concerned about the osprey leaving the eggs open to the air after the first two were laid — wouldn’t they get cold? Not a problem: for one thing, the weather has been quite warm, and the parents know exactly what’s the right temperature for the eggs. Another reason is to wait until the third egg to implement “hard incubation”. This decreases the time between hatching for the three eggs, keeping the youngsters closer in size.
Monday night, April 11: Rosie laid the third egg for the 2022 season in stormy weather conditions.
Congratulations, Rosie! After an extra-long wait that had everyone pacing aimlessly in anticipation, Rosie laid her third egg at 8:42 pm.
It was a long day for Rosie and Richmond, with rain in the morning and high winds to brace against all afternoon. Fishing is difficult in these circumstances, and Richmond did not bring a fish to Rosie today. After laying her egg, she promptly laid back down and has been resting since. With no fish on a rainy, windy day, Rosie appears exhausted.
The weather cleared up Tuesday but was still very windy. Richmond likely tried fishing but couldn’t catch anything in such choppy water. He’d come by the nest for a look see at the new egg but Rosie did not allow him to incubate, sent him off to get some food. She was watching every direction intently all day. In fact, he didn’t show up with a fish until Wednesday, when Rosie had gone 44 hours with no food, almost two days.
It’s generally breezy on San Francisco Bay, so the osprey are used to it, but spring can be stormy. This was such a time. In nature, in real life, there is drama of all kinds, and can make life difficult for wildlife. It’s a reminder of their fortitude and resilience, and general hopefulness.
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Incubation
Co-incubating
Female ospreys typically do 95% of the incubation. Richmond is unusual in that regard: he LOVES to incubate. Once the eggs hatch he’s not so keen to cuddle his offspring. But during the 5-6 weeks of incubation Rosie sometimes has to kick him off the eggs. Sometimes he pretends not to notice her insistent nudging. Rosie is much less amenable to nudging, and at times he’ll make do with co-incubating beside her.
Richmond brings trout
Rosie and Richmond usually raise three chicks. That takes a lot of fish, and that’s where Richmond really shines. He has mad fishing skillz, consistently hauling in one after the next. If anyone can catch a fish in stormy conditions, it’s him. His record (so far) is 12 fish one day before lunch! with a couple more in the afternoon. That was during peak nestling time when they were growing rapidly. Between San Francisco Bay and the San Pablo Reservoir seven miles away, these osprey find ample fish. The SF Bay Osprey website graphed the 2019 season’s fishing data, and you can see how productive Richmond is especially. Once the chicks fledge in early July, Rosie shares the fishing until migration time approaches.
From SF Bay Osprey Cam site, Golden Gate Audubon Society
The vast majority of fish brought in are Striped Bass and Jacksmelt, though more than a dozen kinds of fish have been reported. In recent years, they’ve been enjoying trout quite often.
From SF Bay Osprey Cam site, Golden Gate Audubon Society
Golden Gate Audubon encourages nest cam viewers to watch for and report these fish deliveries. A moderator confirms time and identity. There’s a running log of fish brought to the nest. Here’s a recent excerpt. Note the gap around egg #3 during that stormy interval. Also note that Rosie went out fishing a couple days after laying her third egg. Richmond enjoyed some quality incubation time that day.
From Golden Gate Audubon site, the Fish Counting Matrix at the SF Bay nest cam page
(Date, Time, Fish species, Fish catcher, Notes)
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Golden Gate Audubon Society
Golden Gate Audubon Society
The annual nesting season has just begun for the Whirley crane osprey pair. Rosie and Richmond are excellent parents and we can soon look forward to the wild and lively days of bobbleheads, dinosaurs, wingercizing and all. Then in late August the fledglings will leave, and Rosie and Richmond will have some quiet time together to bookend the season before she departs for the south.
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If you’d like to follow the action, check out the two live cams at San Francisco Bay Osprey Camera.
What’s the birdy action in your part of the world?
