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Posts Tagged ‘Natural History’

A few years ago I wrote a post on niche partitioning amount herons and egrets. That post was inspired by watching several species of herons and egrets foraging for food along Putah Creek near Davis, CA, and the resource they were partitioning into niches was food.

Recently, as part of my work at the Sacramento-San Joaquin Delta Conservancy, I encountered another example of niche partitioning by herons and egrets. This time, the resource these birds are partitioning into niches is nesting trees.

One of the grants that I manage at the Delta Conservancy is at the Cosumnes River Preserve and it includes and grove of large Valley Oak Trees that many herons, egrets, and cormorants use as a rookery (a rookery is a colony of breeding animals, generally birds). One way that the various species have evolved to utilize the same trees, and yet avoid directly competing with each other, is for each species to utilize a different part of each tree to nest in.

Great Blue Herons typically nest on the very tops of the crowns of trees, Great Egrets typically nest only in the upper one-third of the canopy, Snowy Egrets typically nest in the middle one-third of the canopy, and Black-crowned Night-Herons prefer to nest in the lower one-third of the canopy (see the image below).

Niche partitioning of nesting locations within a tree by heron and egret species

I think this stratifying of nesting locations is amazing! Species have evolved to fill so many different niches, and so many niches can be divided into finer and finer gradations. I wonder if there is really any limit to how many species can evolve, and how complex an ecosystem can develop, in a give location.

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A few mornings ago, I was sitting at our kitchen table eating breakfast with my family. As we eat and talked, I looked out through the sliding glass door toward the bird feeders we have hanging out there. This time of year, our feeders get some pretty good activity. As I watched, the usual House Finches, White-crowned Sparrows, Golden-crowned Sparrows (a lot of them this winter), and Mourning Doves were poking around eating sunflower seeds.

But then something amazing happened! A bird hooped up to the top of the wall that defines one side of our yard. This bird was new. This bird was slightly smaller than the White-crowned Sparrows (which are themselves slightly smaller than the Golden-crowned Sparrows). This bird had a clear, white triangular patch at its throat. This bird was a White-throated Sparrow!

Photos - White-throated Sparrow - Zonotrichia albicollis - Birds of the  World
A tan morph White-throated Sparrow like the one I that visited my yard (Photo credit: Birds of the World).

White-throated Sparrows (Zonotrichia ablicollis) are a mostly eastern species. A spattering spend their winters on the west coast, but not many and finding one is always a real treat. This is the first White-throated Sparrow I have ever seen in our yard making the 75th bird species to be added to the yard list!

This species has a bunch traits that make it a bit odd and very interesting. One is the there are two different color morphs, one with white stripes on the head, and other has tan stripes. A related oddity is how these color morphs (which are genetically determined) are maintained in the population. Males of both morph prefer females that have white stripes, but females of both morphs prefer males with tan stripes. A final oddity is that White-throated Sparrows sometimes breed with Dark-eyed Juncos! The two species are not particularly closely related, nor do they look or sound alike. I have never seen one of these hybrids, but I really want to.

Like I said, a really odd and interesting bird, my favorite member of the genus, and a very exciting visitor!

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Audubon's Yellow-rumped Warbler 01

An adult male Audubon’s Yellow-rumped Warbler

In my December article for Berkeley Hills Living, Montclair Living, and Piedmont Living magazines, I decided to focus on the Yellow-rumped Warbler and the idea that this one species may be split into several. Take a look!

2019.12 BerkeleyHillsLiving_Final2019

 

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Phoebes 02

A Black Phoebe

I have been writing a monthly article for a set of three neighbor magazines for the past couple of years now. These magazines are distributed to a handful of east bay neighborhoods. I have shared one or two of the articles in previous posts, and am thinking of doing so more regularly, so here is the article on Phoebes that I wrote for the November issue of Berkeley Hills Living, Monclair Living, and Piedmont Living magazines.

Berkeley Hills Living – November 2019 Issue

Phoebes 01

A Say’s Phoebe

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Rich Stallcup Bird-a-thon 2019 logoPoint Blue Conservation Science has a blog called Science for a Blue Planet that highlights the great work done by this organization. The blog post reporting on the 2019 Bird-a-thon features the Drake’s Beach Sanderlings!  It is really wonderful to get this kind of acknowledgement, and exciting that the Sanderlings might be the high species total winner this year!

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Rich Stallcup Bird-a-thon 2019 logo

Dear Sponsor,

The Drake’s Beach Sanderlings was the first, and is the longest running, youth Bird-a-thon team that the Point Reyes Bird Observatory has ever organized. I was one of the founding youth members and am now the team leader.

Since its beginning, the Sanderlings have established a very successful tradition of crisscrossing Marin County every fall, finding as many bird species as possible in twenty-four hours, and raising money for bird research and conservation. During the 2018 bird-a-thon, the Sanderlings were particularly successful when we found more bird species than any other team that year! Over the years our team members have changed as our youths get older, move away, or enter college. Wherever they have spread, Sanderlings members carry a passion for birds and nature with them that was, in part, nurtured by our team.

We are now preparing for our 2019 bird-a-thon! To support this team, I would like to invite you to become a sponsor of the Sanderlings. Your support sends a powerful message to the birding community that a team of young people can make an important contribution to bird conservation. This year, the Sanderlings bird-a-thon will be on October 5th. When you become a sponsor, I will be sure to let you know how the day goes.

Becoming a sponsor is easy! Just go to: https://pointblue.securesweet.com/contribute_paymentspring.asp?userid=1&fundid=832 and enter your info, or follow the QR code, below. I hope you are able to support this wonderful team. Please feel free to contact me with any questions you might have.

 

Sincerely,

Aaron

Drake’s Beach Sanderlings Team Leader

QR Code - blog

Sanderlings 2018 Team Photo

The 2018 Drake’s Beach Sanderlings.

 

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In 1982, the year I was born, there were only 22 California Condors alive in the world. Those 22 birds were all that remained of a population that once spanned the western US, and bits of Canada and Mexico. The Condor population plummeted as a result of lead poisoning, hunting, habitat loss and pollution.

California Condor 01

Geographic range of the California Condor in the 1880s

By 1987, the world population of California Condors was 27 birds. Since the causes of the California Condor decline were distinctly human activities, it only seemed appropriate for humans to step up and attempt to fix what they had broken. To that end, the 27 birds were captured and taken into a captive breeding program run by the U.S. Fish and Wildlife Service. The goal of that captive breeding program was to first raise Condors and establish multiple captive breeding populations, and then to establish multiple wild populations. It was an ambitious plan.

Over the last 37 years, the program has overcome countless challenges from figuring out how to hatch condor eggs, to how to raise babies that will grow into wild adults, to teaching those young adults to find food. California Condors are not fast breeders. A pair will only lay one egg each year, and they sometimes skip years. The young birds take several years to grow and gain full independence, and will begin to breed after about five years. It has taken extensive amounts of money and time, but success after success have become realities.

California Condor 03

An adult California Condor

A small number of captive breeding populations were established in zoos raptor breeding facilities. In 1992, Condors began to be released into the wild. Additional releases established small populations in California, Arizona, Utah, and Mexico.

Now a new milestone has been reached. In March of this year, the 1000th California Condor chick has hatched since 1987 when the captive breeding population was initiated. This brings the living population to around 500 individuals, since numerous chicks, juveniles, and adults have died in the last 37 years. The 1000th chick hatched in the wild to a pair of Condors living in Zion National Park in Utah.

A population of 500 individuals is still not big enough to be out of danger of extinction, and as such are still protected by the U.S. Endangered Species Act. But it is certainly a wonderful accomplishment, and the 1000th chick born is also a occasion to be celebrated. Hopefully, the California Condor population will continue to grow, and the amazing birds, the largest in North America, with their 9 foot wingspans will be circling 15,000 feet over our heads in greater numbers and across greater areas as the next 37 years unfold.

California Condor 02

 

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I spent the 4th of July weekend camping with my family at one of my favorite spots. Domingo Spring in Lassen National Forest. I first visited this site during my graduate school work where I was recording the calls of Evening Grosbeaks, and I have returned regularly ever since. The campground, set among jumbled piles of volcanic rocks and large conifer trees, is immediately beside a wet meadow that Domingo Creek runs through. Near the entrance of the campground is the source of Domingo Creek, and the campground’s namesake, Domingo Spring. This spring is one of the few places I know of where one can drink right out of the land. In my mind, that makes this a very special spot, indeed. We also drove to Willow Lake for part of one day which was lovely. Willow Lake has a floating sphagnum bog where a couple of native species of carnivorous plants grow wild.

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My brother birding Domingo Spring

The days we spent camping were filled with birds, a lake visit, walks throughout the surrounding meadows, lots of cooking over the fire, singing, talking politics, reading the Declaration of Independence on the 4th of July, drawing, and so much more! One bird encounter that was really wonderful was our neighbors in the campground. A pair of Cassin’s Vireos had a nest about 25 feet up a ponderosa pine tree at the edge of our campsite where four nestlings eagerly gobbled down each of the insects their parents delivered. Many Western Tanagers, including a lot of newly fledged birds, were also around this year.

The full species list for birds included: Mallard, Common Nighthawk, Anna’s Hummingbird, Turkey Vulture, Great Horned Owl, Black-backed Woodpecker, Hairy Woodpecker, White-headed Woodpecker, Pileated Woodpecker, Northern Flicker, Western Wood-Pewee, Stellar’s Jay, Common Raven, Tree Swallow, Mountain Chickadee, Red-breasted Nuthatch, Brown Creeper, House Wren, American Robin, Cassin’s Vireo, Evening Grosbeak, Purple Finch, Cassin’s Finch, Song Sparrow, Lincoln’s Sparrow, Red-winged Blackbird, Orange-crowned Warbler, MacGillivray’s Warbler, and Western Tanager.

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My daughter holding a Pacific Tree Frog

We also had some nice herpetological encounters. I caught a small Mountain Gartersnake, and my wife and daughter caught a Pacific Tree Frog. Oddly, we did not see any gartersnakes are Willow Lake. In the past we have often seen them swimming in the lake as they hunt for minnows in the water, sometimes around our feet. This year, the water was much more turbid that it usually is (a result of the fairly recent snow melt?), and maybe this made the water less appealing as hunting grounds for the snakes that are pretty visual predators.

Mountain Gartersnake - Domingo Spring - 20190705

Mountain Gartersnake

Mammals we saw included Mule Deer, California Groundsquirrel, Golden-mantled Groundsquirrel, Douglas Squirrel, and Allen’s Chipmunk.

I very much look forward to the next time I return to Domingo Spring to enjoy the mountains and drink from the rocks.

 

 

 

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Homosexuality has been observed is just about every species it has been looked for. Transgender animals are not as widely known, but may just be a matter of looking for them.

There are certainly some animal examples that are various forms of transgender animals in nature. One is the California Sheephead (Semicossyphus pulcher) which is a fish that is born female, and then can become male later in life. Another example is found in the Green Frog (Rana clamitans) that reverse sex in response to various external factors, and this has been observed in other amphibians as well. But both of these examples are in lineages of animals that are pretty distantly related to us humans.

lionesses-with-manes

Photo of two lions one is male sex (left), one is female sex (right), but both display male characteristics.

Well, research published a couple of years ago in the African Journal of Ecology is an example much closer to us. In a paper by Gilfillan et al. from the University of Sussex, five lionesses in Botswana have been observed to grow manes, regularly roar and scent mark, mount other females, and display other very male-like behaviors such as killing the cubs of rival prides which females lions just about never do but is very common for male lions.

This is a mammal we are talking about.

Lions that are female in body, but male in behavior.

In the wild.

Still think being transgender is unnatural?

Transgender Flag

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A news story has been circulating a fair bit in the past couple of weeks. This story has been picked up by numerous news and science outlets. How it is being reported and explained is just plain misleading and inaccurate.

Image result for aldabra rail

The Aldabra Rail is a subspecies of the White-throated Rail.

Here are a few titles that show how the subject is being covered.

Science Magazine – Evolution Brings Extinct Island Bird Back into Existence

Smithsonian Magazine – How Evolution Brought a Flightless Bird Back from Extinction

CBS News – An Extinct Bird Species Has Evolved Back into Existence, Study Says

From these titles, and from the bodies of the articles themselves, readers would think that the same species of bird existed at some point in the past, went extinct (as in died out completely), and then re-evolved!

That does not happen.

Here is what actually did occur.

The small atoll of Aldabra is a pretty spectacular spot. It is very remote. It is quite beautiful. It is home to a bunch of unique animals found no where else on earth. It has one of the longest fossil records on any island in the Indian Ocean.

That fossil record includes a lot of the animals that have called the atoll home over the past few million years. One of those animals was the Aldabra Rail. This rail was a small flightless bird that was probably found hunting through reed beds along the edges of water. The Aldabra Rail went extinct about 136,000 years ago at about the same time that global sea level was rising and submerging oceanic islands like Aldabra. After a few thousand years, sea level dropped and Aldabra became an exposed island once more. Not long after that fossils of a rail on Aldabra start showing up again.

There are a couple of possible explanations. One is that some remnant population of the Aldabra Rail hung on, some how, and did not die. These were flightless birds, so it is not clear how this might have happened, but perhaps a small population managed to survive on a floating raft of vegetation long enough to reach an exposed bit of land. This seems like a very long shot. It is much more likely that the Aldabra Rail simply died out completely. It went extinct.

The other possible explanation is much more likely and widely understood and accepted, and it is this: the Aldabra Rail went extinct when the atoll went under water. Then after it re-emerged, a group of birds likely from the same parent stock of the original Aldabra Rail re-colonized the atoll (quite probably from Madagascar). This new group of colonizers eventually became flightless and filled the same, or very similar, ecological niche as the original Aldabra Rail.

This is a process called iterative evolution and it is pretty rare. The definition of iterative evolution is: the evolution of similar or parallel structures in the development of the same main line.

But iterative evolution does not produce the same species twice. It may produce similar species, but to produce the same species twice would require starting with the same gene pool twice. The group of birds that first colonized Aldabra, and became the Aldabra Rail 1.0, had a unique combination of genes to work with. The group of birds that later colonized Aldabra, and became the Aldabra Rail 2.0, had a unique combination of genes to work with. Those two combinations of genes may have been similar, but they were not the same. Therefore the decedents of those two groups would not be the same.

I really think that the implications of how this story is being reported is really misleading and possible even damaging.

Misleading because they imply that a species can evolve twice. To go back to the definition of  iterative evolution, it the evolution of “similar or parallel structures…” Similar or parallel structures are not the same as identical species. Two rails that evolved at different times in the same place and that are both flightless, are not the same species.

Damaging because there is weight to the idea of extinction. Extinction is forever. It means that an entire evolutionary lineage has ended, and any potential future that that lineage may have had is gone. If the idea of extinction becomes an impermanent one, it looses its urgency and tragedy. People may well not worry about extinction as that species can just re-evolve. No harm, no foul.

Again, no species can ever occur twice. Once a species goes extinct, that is it for that evolutionary lineage. Even if some other lineage emerges that is close, it will not be the same and will not have the same evolutionary trajectory or potential.

When reporting on science, I feel strongly that the ideas behind the science should be accurately represented. I think it is especially distressing when the sources of the misrepresentations are otherwise reputable sources for science.

I hope the current Aldabra Rail has a long future filled with descendants, and I mourn the loss of the previous rail of Aldabra and the lineage it might have left behind, but never will.

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