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Archive for the ‘Natural History’ Category

I spent last weekend in the wonderful little town of Bolinas, CA. This special spot on the California Coast a relatively short drive north of San Francisco is a quite and quirky and very laid back. It is also right on the shore of the Pacific Ocean and Bolinas Lagoon and as such it provides access to a bunch of coastal and aquatic habitats, and I took advantage of this positioning to do a lot of birding!

Wildlife photographer captures osprey carrying shark, carrying fish in  'one-in-a-trillion photograph' | Fox News
Osprey carrying a fish. Photo Credit: Fox News

One morning, I went out to the beach to see what coastal and ocean birds I might spot and to do a bit of beach combing while I was at it. The sky was gray over the ocean, but not foggy. The tide was low and it was fun to spend a little time looking at washed up kelp, finding Sand Crabs as the waves broke on the shore, and looking out to sea at the rolling ocean. I was also enjoying watching the Western Grebes and Clark’s Grebes fishing off shore, the Double-crested Cormorants flying back and forth, and the Brown Pelicans cruising above the waves when I heard a bit of a commotion overhead. I looked up to see three birds chasing each other around in a mid-air tangle. One bird was an Osprey with a fish in its talons. The second bird was an adult Western Gull trying to steal that fish. The third bird was an adult Bald Eagle also trying to rob the Osprey! All three birds were engaged in some fancy flying over the waves as they attempted to secure their breakfast as the sun rose above the tree topped hills.

Sound Library - Bald Eagle - Yellowstone National Park (U.S. National Park  Service)
Adult Bald Eagle. Photo Credit: National Park Service

The tangle of birds did not last long. The Osprey was ultimately successful at defending its catch from the two would-be thieves and flew off to enjoy its meal. The gull quickly disappeared to forage elsewhere, but the eagle stuck around for a little while. It circled out over the Pacific for a couple of minutes, and watching for so long was a real treat for me. It then turned toward shore, dropped altitude, and flew along the beach. As it spread its huge wings about 50 feet over the sand, it flew slowly over beach goers and surfers. None of whom noticed at all! The humans were all absorbed in their own activities and did not realize that an enormous, not to mention iconic, bird was cursing right over their heads. I suppose that I should not have been surprised by this lack notice, and to a certain extent I wasn’t, but it was definitely amusing.

The Bald Eagle continued flying smoothly down the beach until it followed the bending line of the sand around a bluff and out of sight, and I continued my morning of beach exploration. It was a lovely morning that I enjoyed very much, and I hope you get out for some time on the coast as well.

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Mute Swans (Cygnus olor) are a species that is growing more and more numerous, and this is a problem.

Mute Swans are the “classic” swan from stories and art. They are large and showy and beautiful and these traits are exactly why they have been introduced to North America. Birds were brought from Europe in the 1800s and released in parks, gardens, etc. as ornamental additions (New York was the original release area). These birds have since reproduced and spread across the continent as far north as New Hampshire, as far south as Florida, and as far as west as California.

Adult male Mute Swan (Cygnus olor). Source: USFWS digital library.

They are becoming problematic for several reasons. One is that they are quite aggressive, and will chase and bite humans if that human trespasses on the swan’s territory. Another is that they consume quite a bit of food. They are big birds reaching up to 25 to 30 pounds, and that means they eat about eight pounds of aquatic vegetation every day. That is food which is then not available to native birds, and it disrupts habitat for native birds, mammals, fish, and other species. And a third reason is that the swans are directly aggressive to other species of bird driving them off nests, breaking eggs, and killing the chicks of other species, and so displacing those other species from areas where they would otherwise live. With habitats becoming ever smaller and more fragmented, this can mean the native species can be left with no where to go.

These problems have all contributed to Mute Swans being added to California’s restricted species list in 2008. This listing means the birds cannot be imported, transported, or possessed in the state without a permit. This has not completely prevented the swans from beginning to become established in California. Small populations can be found in Petaluma and the Suisun Marsh. I suggest that removing this species while the population is still small is the best course of action. There is every reason to suspect that the population will grow, and as it does so, the problems listed above will become more and more apparent. However, control will become more and more difficult.

One interesting thing about Mute Swans in North America is that they do not migrate very much. There are certainly some, relatively short, seasonal movements that occur in some parts of the continent, but not much. Certainly nothing compared to the long migrations that Mute Swans in Europe engage in. The evolution of this behavior in a novel environment illustrates how different geographic regions can cause a species to adapt and change. This behavioral evolution could then lead to the evolution of a new species, if it persists and becomes dramatic enough.

So, what can you do to help native birds and habitats, and prevent Mute Swans from taking over? If you spot a Mute Swan in California, contact the California Department of Fish and Wildlife – Invasive Species Program by sending an email to: invasives@wildlife.ca.gov or calling 886-440-9530. Together, we can act as citizen scientists to gather data that tracks where these birds are and how they move around. This data will help us all make the best and most informed decisions we can about this species.

Thanks for visiting my blog. If you are interested in other ways to connect with me, here are a couple of options:

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A few years ago, I wrote a post called Lizards, Ticks, and Lyme. It explained how Western Fence Lizards (Sceloporus occidentalis) have a blood protein that kills the bacteria that causes Lyme Disease, and this is one of the major explanations of why Lyme Disease is so much less common in the Western USA.

Well, new research (see references at the end) has added a really intriguing facet to the Tick-Lizard-Lyme story. This new research focuses on the southeastern USA. The southeast is another area where Lyme Disease rates are very low. But why? The southeastern USA has populations of Black-legged Ticks (members of the genus: Ixodes), which are the ticks that can carry Lyme Disease. The region has the mammal species such as deer and mice that act as reservoirs for Lyme Disease. People in the southwest get bitten by ticks, just like other parts of the country. So why is Lye Disease so much more common in the northeastern USA than the southeastern?

Well, once again, it looks like we can thank lizards. Skinks are a group of smooth-scaled rather lovely looking lizards and they are one of the preferred hosts for ticks in the southeastern USA. In the northeastern USA mice are the much more common host to ticks. And this sets up a roadblock for Lyme Disease in the southeast because skinks have been shown to be really bad transmitters of Lyme Disease. Mice, on the other hand, have been shown to be very effective transmitters of Lyme Disease.

A Southeastern Five-lined Skink (Photo credit: Animal Spot)

It is not yet known if the stinks blood contains proteins that actually kill the Lyme Disease-causing bacteria, or it there is something else about skinks that reduces transmission rates, but this difference in host does help to explain why Lyme Disease rates are so much lower in the southeastern USA as compared to the northeastern USA.

So, fence lizards and skinks both contribute to reducing Lyme Disease in the areas where these lizards are found. Pretty fascinating stuff! I am very much looking forward to learning more about this subject as more research is done. Do other lizard species also reduce the occurrences of Lyme Disease? Does skink blood kill the bacteria that causes Lyme Disease? What is the blood protein that the fence lizards produce that kills the bacteria, and can it be synthesized? So many questions!

I hope you follow this story, and are as intrigued by it as I am. I will certainly write more as more is discovered.

Here are some sources for further reading: a Science News article, and an SF Gate article.

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Bee populations have been having a hard time for a while now. Species of bee all around the world have experienced significant population declines that have persisted for decades. But it has been difficult to get a sense of the full magnitude of the issue since so many of the bee population studies focused on a single species, or a relatively small geographic area.

In 2020, researchers at the National University of Comahue in Argentina took a more global look at the loss of bee diversity. These researchers published a paper used data from the Global Biodiversity Information Facility which is a platform where researchers and citizen scientists can record sightings of bee species, and that is available to the public.

By examining observations of bees around the world they found that the number of bee species observed from 2006 to 2015 was only about 75% of the number of species observed before 1990. That is not a very long period of time, and these declines were despite the fact that more and more observers are adding more and more observations to the platform each year. To clarify, this does not mean that 25% of the world bee species have gone extinct, but it does mean that they have become so rare that people are not encountering them. Although, becoming extinct is one potential reason for no longer being observed.

One of the bee species, in particular, that has declined rapidly is the Rusty-patched Bumble Bee (Bombus affinis) which was once found across much of the mid-western and northern USA. This species has declined by nearly 80% since the late 1990s. This decline lead the United States Fish and Wildlife Service to list the species as federally endangered in 2017. This was the first species of wild bee in the continental USA to ever be federally listed and so gain the protection of the Endangered Species List (several species of bee native to Hawaii have been given this status prior to the Rusty-patched Bumble Bee).

Rusty-patched bumble bee on culver’s root at University of Wisconsin–Madison Arboretum. Photo: Susan Day/UW–Madison Arboretum.

The listing of the Rusty-patched Bumble Bee and the research on the dramatic and sustained reduction in abundance of global bee biodiversity both serve to highlight the loss of bees and other insects. This is an often overlooked section of lost biodiversity. The extinction of a rhino species is much more eye-catching than the extinction of a bee species. But loosing bees and other insects is having, and will continue to have, profound impacts on the natural world around us, and so should not go unnoticed!

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Have you ever seen a v-shaped flock of geese fly overhead and wondered, why do they do that? In this video I share some information explaining this interesting behavior. I also talk about the other species that also fly in v-shaped flocks, and dispel an oft repeated myth.

If you enjoy the videos I am creating, two ways to stay informed would be to subscribe to the A Birding Naturalist channel and/or become a follower of this blog.

Eurasian Cranes (Grus grus) flying a v-formation (Photo courtesy of Wikipedia)

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This video is from a recent visit my family and I made to Staten Island in the central Sacramento-San Joaquin Delta. Staten Island is a 9,200 acre reserve owned and managed by The Nature Conservancy specifically to provide foraging and roosting habitat for Sandhill Cranes (Antigone canadensis) and also waterfowl, shorebirds, and many other species.

If you enjoy the videos I am creating, two ways to stay informed would be to subscribe to the channel and/or follow this blog.

Sandhill Cranes (Photo courtesy of the USFWS – John Magera)

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I have been working at the Sacramento-San Joaquin Delta Conservancy (Delta Conservancy) for about five years, now. In that time, one of the major projects I have been working on is our Proposition 1 Grant Program. Proposition 1 was a water bond passed by voters in 2014. Among many other things, it allocated $50 million dollars for the Delta Conservancy to give out to fund projects that would restore habitat, improve water quality, and/or support sustainable agriculture within the legal boundary of the Sacramento-San Joaquin Delta. A large part of my role here has been to help form the competitive process by which organizations can apply for this funding, and then to manage the grants that fund the selected projects.

One such project is the Dutch Slough Tidal Habitat Restoration Project. This is a project being organized by a team including staff from the Department of Water Resources (DWR), the local reclamation district (RD 2137), and several consulting firms.

This project is a huge one! About 1,160 acres in size, this project represents one of the larger habitat restoration projects occurring in the Delta. And it is restoring extensive amounts of tidal habitat, which makes it an even bigger deal since tidal restoration is difficult from both technical and political standpoints. These difficulties help to explain why it has taken about 15 years for this project to go from concept to implementation. Since it is so large, funding has come from several different sources with funds from the Delta Conservancy awarded to cover the costs of the revegetation phase.

Partly as a result of how high profile a project this is, DWR has created some great materials for telling people about the project. One of the best is a short video about what the project is, how it came to be, and what the hopes for the project’s future include. I highly recommend giving this video a watch. Another amazing way to explore the project is their YouTube channel. This channel has dozens of videos. They are drone flights over the project taken over the past three years. Going and watching some of the earlier videos and comparing those with more recent videos is pretty breathtaking. These before and after videos provide a wonderful example of how dramatically, and relatively quickly, habitat restoration projects can change a landscape and create habitat.

I hope you enjoy the virtual exploration. The project will have trails that are open to the public when it is completed (likely next year), and I encourage you to head out to the site in person when that happens.

Image taken from one of the drone flight videos from 2020

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A few years ago I wrote a post on niche partitioning among 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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On October 3rd, 2020 I took part in a very unusual bird-a-thon.

The Point Blue Conservation Science Rich Stallcup Bird-a-thon is an event I have been participating in for about 20 years, now, and have written about numerous times on this blog (see the links at the bottom of this post to read some of them). The team I bird with is named the Drake’s Beach Sanderlings, and we are the longest running youth bird-a-thon team I know of. I started as a youth member of the team, and have now been the team leader for the past few years. It is a great team of very talented and passionate young birders.

The usual plan for the Sanderlings is to gather very early one morning in late September or early October in Marin County, and spend the entire day darting all over the county to find as many species of bird as we possibly can. It is always exhausting and exciting and terrific!

However, as with some many other aspects of life, 2020 is different. Instead of meeting in-person Point Blue decided on a few different ways for people to participate in the event. The Sanderlings decided to each go out and bird, and then combine each of our individual totals. This is not at all comparable to past bird-a-thon years since each team member would be in a different area and have access to different habitats with different species. But it is still a great way to go birding and raise funds for a terrific organization!

For myself, I decided to set a challenge of birding within the city limits of my home town, West Sacramento, CA. Unfortunately, the wildfires that are burning across much of state made the air quality pretty bad, so I was not able to stay out and bird for the whole day.

But, my West Sac Big (half)Day was still a fun challenge! I ended up finding 82 species! Some of my highlights included a late Barn Swallow; a single Greater White-fronted Goose; a wonderful mixed flock of Savannah Sparrows, White-crowned Sparrows, Western Bluebirds, and Say’s Phoebes; a really spectacular Yellow Warbler that let me get really close; a handful of Blue-winged Teal mixed in among hundreds of Cinnamon Teal; lots of Lincoln’s Sparrows throughout the day; a flock of Sandhill Cranes bugling as they flew overhead; and stumbling upon a small flock of Least Sandpipers. Some notable species that I missed included Osprey, Fox Sparrow, and many of waterfowl that I thought I would get such as Snow Goose, American Wigeon, Northern Shoveler, Northern Pintail, and Gadwall.

This event ended up being a lot of fun even though it was a half day because of smoke and I was alone because of COVID-19. I am definitely interested in trying the West Sac Big Day again. Maybe in a different season (I think winter would probably get me the highest species total), and definitely for a whole day.

Stay safe. Wash your hands. Wear a mask.

Here are some other posts on the Drake’s Beach Sanderlings:

https://abirdingnaturalist.wordpress.com/2019/11/13/the-2019-drakes-beach-sanderlings-bird-a-thon-report/

https://abirdingnaturalist.wordpress.com/2017/09/29/the-drakes-beach-sanderlings-rogue-year/

https://abirdingnaturalist.wordpress.com/2013/09/30/why-i-bird-a-thon/

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