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Posts Tagged ‘raptor’

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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If you are in the Davis or West Sacramento area in the late summer or early fall, and have an evening to spare, go and find a spot where you can sit beside the Yolo Bypass Causeway. This is where highway I-80 crosses over the Yolo Bypass.

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Streams of Mexican Free-tailed Bats over the Yolo Bypass

Just as the sun begins to set, you will see an amazing sight. Columns of bat will flood out from under the bypass and stream across the sky in sinuous ribbons. About a quarter of a million Mexican Free-tailed Bats (Tadarida brasiliensis) live under the bypass this time of year, and every night they pour out and spread across the surrounding area to find small flying insects to eat.

These bats are incredible! They can fly about about 100 miles per hour, making them among the fastest mammals in the world! Remember that Cheetahs are the fastest land-mammal, but bats have them beat by a healthy margin. These bats can fly as high as a mile above the ground, and can forage out distances of several miles from their night roost before returning around dawn to sleep. Using their sonar they can detect and pinpoint the exact position of little insects flying through the air and then capture those insects on the wing, at speed!

My wife, daughter, and I joined some friends and went out for an evening visit to see the bats about a month ago. I was a spectacular evening in the Yolo Bypass Wildlife Area. We saw lots of Swainson’s Hawks; herons, egrets, and ibis galore; some of the biggest Western Saddlebags (which is a species of dragonfly) I have ever seen; and then we got to the causeway.

When we arrived, the sun was still a touch above the horizon, so we had some time to stand around the dirt road that runs parallel to I-80 and chat and watch the sunset. We got a very nice surprise when an adult Peregrine Falcon flew past and landed in the top of a tree a little ways to the west of us. I was so excited to see this bird that, in turning around for a better look, I clumsily stepped on my wife toes (sorry sweetheart)!

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Mexican Free-tailed Bats as they leave from under the Yolo Causeway.

As the light began to fade, we started seeing little movements under the causeway. The first bats were starting to move. Interestingly, the bats do not wake up, take flight, and simply fly out from under the causeway wherever they happen to be. Instead, they wake up, take flight, and then fly directly under the causeway for a few hundred yards before turning a sharp left, and lifting up into the open sky. I have no idea why they decide to do this, but volunteers at the Wildlife Area know it is gong to happen so consistently, that they can tell you exactly which tree the bats will fly out near.

The numbers of bats moving under the causeway built and built until there were bats streaming along between the support pillars. Then they made that left, and out in to open they came! A snaking stream of bats began raising and twisting into the sky! Thousands and thousands of bats following one another out from where they had been sleeping to look for food. As we watched the seemingly endless flow of bats, we got a very cool surprise. That Peregrine Falcon that we had seen earlier came back. It started strafing through the flow of bats. It was hunting bats!

I have seen this behavior of raptors hunting bats as they leave their night roost on video before, and it is pretty spectacular to see on a screen. Seeing it in real life was thrilling! After a couple of passes, the Peregrine made a quick move to one side, and suddenly it had a bat in one talon! It flew off and out of sight carrying it’s dinnertime snack.

The rest of the bats were generally nonplussed by the Peregrine attack, and keep streaming and streaming into the coming night.

Finally, the last bat that was going to leave had departed, and the darkness was getting deep enough that we would not have been able to see the bats fl by even if they were there, so we piled back into our cars and headed for home.

All in all, a terrific way to spend and evening!

 

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A friend of mine has been volunteering with the National Park Service to track the nesting activities of raptors in the Presidio in San Francisco, CA for the past twenty years. There are four species of bird of prey that nest in the park. They are Red-tailed Hawk, Red-shouldered Hawk, Cooper’s Hawk, and Great Horned Owl.

Information that has been collected include where these birds nest, how many nest in the park, when stages of nesting (breeding, egg laying, incubation, etc.) occur, how many chick fledge from each nest, etc.

This project has taken a wonderful turn this year with the installation of nest cams! My friend, and others, have been working with the Park Service to get funding to purchase and install nest live-cams on some of the active nests. One of the first such cams has now been installed on a Red-tailed Hawk nest that has been built between the branches of a Blue Gum Eucalyptus Tree. The live-stream of this nest cam can be found on YouTube HERE.

RTHA Nest Cam Capture

Male Red-tailed Hawk in the Presidio, San Francisco, CA incubating the one egg that had been laid at this point. Note thin, black barring that are restricted to near the base of the tail.

The pair of Red-tailed Hawks have laid one white, and lightly speckled egg in the nest as of 3/7/2018. The male and female can be distinguished by a few characteristics. The best is by tail pattern. The male has a few, very thin black bars on its red tail. These bars are limited to the base of the tail. The female, on the other hand, has those thin black bars on the tail that extend just about all the way down to the black subterminal band near the tail tip. Beyond these tail pattern differences, the male and female have different molt patterns on the secondary flight feathers, the male is slightly smaller than the female, and the male is banded!

RTHA Nest Cam Capture F

Female Red-tailed Hawk in the Presidio, San Francisco, CA incubating the one egg that had been laid at this point. Note the thin, black barring that extend all the way to the subterminal tail band.

I have already noticed a few interesting things after only checking in on the nest for a couple of days. One is that when the the male comes to the nest to give the female a break, he sometimes brings nesting materials to add to the nest. He does this even though the nest is complete and an egg has been laid.

So far, about 60 people have been watching the nest at any given time. I am sure that this number will go up, and it will be great to push it as high as possible, since I am also sure that the Park Service will be more inclined to install more live-cams if the public response is positive and strong. So watch the Red-tailed Hawks and see what is going on at  the nest!

 

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The Sacramento-San Joaquin Delta Conservancy (where I know work) was allotted $50,000,000 from the voter approved Proposition 1 for projects that will enhance habitat, improve water quality, and/or increase sustainable agriculture in the Delta. These funds are to be given out over the course of five years, starting with the first solicitation in fall of 2015. The Delta Conservancy created a competitive grant program where applicants can send in proposals and Delta Conservancy staff, with the input from other experts, determine which proposals have the best chance of success and will enact the most valuable projects. This first round of projects could be planing projects of up to $100,000 or implementation projects of up to $2,000,000. A major component of my work has been to help administer this grant process and evaluate the proposals that have applied for the Delta Conservancy’s Prop 1 money in this first year. We, the staff, shepherded projects through the process and made recommendations to our governing board, who voted to approve or reject the various projects that were submitted. Going forward, I will continue to be highly involved in the next 4 years of funding cycles.

Swainson's Hawk - Jabari Bellamy

Adult Swainson’s Hawk hunting over a California grassland (Photo compliments of Jabari Bellamy)

One of the projects that applied for the Delta Conservancy money was submitted by the Environmental Defense Fund to convert approximately 300 acres of private agricultural working land currently used for growing various row crops into pastureland bordered by hedgerows of native vegetation. This crop conversion will encourage Swainson’s Hawk prey species and so make this land high quality foraging habitat for Swainson’s Hawks. This project scored in our competitive process and was approved by our board (pending a some final administrative paperwork). To read more about the project, and find out more about the work that the Environmental Defense Fund is doing, check out this link to their write up of the project.

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A post from AbirdingNaturalist has been accepted to the website NatureWriting! With the acceptance of my piece titled “A Vomiting Vulture,” I am now a contributor. This is the first time one of my posts has been featured on another website, so I am pretty excited!

NatureWriting can be found here.

My post can be found here.

Check them out!

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I was walking along the edge of a plowed field along the Clarksberg Branchline Trail in West Sacramento a couple of days ago when I saw a hatch year Northern Harrier quartering back and forth, low over the ploughed earth. The raptor was not very far from the edge where I stood, so I was able to get a really great view as I watched it coursing along and staring at the ground intently as it hunted for its breakfast. Suddenly, it made a sharp turn, almost flipping over itself, and dove for the ground. It landed on something and after a moment standing on the ground, it took off. As it did so, I saw a small, brown object in its talons. I assumed at first that it was a small mammal, and that the Harrier had made a successful hunt, but when the bird was about 20 feet off the ground, it dropped the brown object. As the thing dropped back to the earth, I was able to see that it was not an animal at all, but was actually a clod of dirt.

What had happened here? Did the Harrier make a mistake and attack a mouse-shaped bit of dirt thinking that it was, in fact, the makings of a meal? Given how amazingly keen the eyesight that raptors possess this seems unlikely. And it seems especially unlikely given that the bird was only about 20 or 30 feet off the ground when it started the dive. Making that big a mistake at that close a range is hard to believe. So what was the hawk doing? Was it practicing? This was a young Harrier. Perhaps, not seeing any actual voles or mice at that moment, it decided to do a little target practice. I don’t think of raptors needing practice, but of course that is probably kind of silly. Young songbirds need to practice their song, and often sound amusingly bad at first. However, of the course of a few weeks, they practice and hone their vocal abilities and end up producing songs that sound like the other adults of the species. So, raptors practicing their hunting skills seems pretty understandable. The amount of skill required to be a predator is rather impressive, and even when you consider that many of these skills are hard-wired instinct, that still leaves a lot of room for learning and improvement: practice. Here was a raptor that, perhaps, just picked a particular earth clod on the ground and wanted to see if it could hit it at high speed, just to see if it could. It did, so that practice run was successful! Practice does make perfect!

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HMANA Press release – October 14, 2014

Over One Million Migrating Hawks Counted during International Hawk Migration Week

Hancock, NH – The Hawk Migration Association of North America (HMANA) celebrated its first annual International Hawk Migration Week (IHMW) September 20-28, 2014 by tallying over 1.2 million migrating hawks, eagles and vultures at 100 sites throughout Canada, the United States, and Mexico.

Each year hundreds of thousands of hawks, eagles and vultures make their journey from Canada and the United States through Mexico to wintering areas as far as South America. Dedicated counters at hawk watch sites document this movement starting as early as 1 August and continuing daily into December. Their daily numbers are reported to HMANA’s online database, HawkCount.org. This particular week in late September was chosen due to the sheer number of hawks that are counted across North America.

One hundred watch sites from 33 states and provinces across the continent counted an astounding 1,203,067 raptors during September 20-28. Twenty-nine species were tallied, the vast majority being broad-winged hawks (1,125,597) – since IHMW took place during their peak migration. Other high counts included 24,899 Sharp-shinned Hawks, 8,909 Mississippi Kites, 8,724 Turkey Vultures and 7,192 American Kestrels.

Raptors tend to follow topographic features during fall migration such as north to south running ridgelines, coastlines, and river valleys. As they move further south, there’s a funneling effect as they approach the southern US. The majority of hawks choose to avoid long water crossings so are then squeezed along the coast of the Gulf of Mexico and on through Mexico. This is why the Veracruz, Mexico watch sites counted more than any other at 812,949 during IHMW. Corpus Christi, Texas located on the US Gulf coast tallied 226,224 raptors. Other counts across the continent included 15,862 at Hawk Ridge Bird Observatory, MN; 4,151 Holiday Beach Conservation Area, ON; 4,811 at the Goshute Mountains, NM and 2,777 at the Florida Keys Hawk Watch, FL.

In addition to submitting their daily migration counts to HMANA’s HawkCount.org database, sites celebrated across the map with hawk watching festivals, identification workshops and live bird of prey events. Dr. Laurie Goodrich of Hawk Mountain Sanctuary, Kempton, PA (the oldest hawk watch site in the western hemisphere) said: “IHMW is a fantastic demonstration of the popularity of hawk watching and the value of raptors in the environment.”

About HMANA

HMANA (www.hmana.org) is a non-profit organization with a mission to advance scientific knowledge and promote conservation of raptor populations through the study, enjoyment, and appreciation of raptor migration. It oversees the online database, Hawkcount.org, an archive of count data with a wealth of information for birdwatchers and general public alike, including maps and directions to sites, average counts, population status and migration timing by species.
HMANA partners with Hawk Mountain Sanctuary PA (www.hawkmountain.org), Hawk Watch International (based in Utah: http://www.hawkwatch.org), and Bird Studies Canada (in Ontario: http://www.bsc-eoc.org) in the Raptor Population Index program, which aims to track changes in hawk populations for conservation purposes.
For directions and contact information for hawk watch sites near you, visit http://www.hawkcount.org.

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