Ask SIB: Mating Behavior of Terns

Several years ago and for several years we used to see a mating ritual among a class of terns in mid Spring. We saw it down at the point by the beach club but they would also appear over our Sealoft villa. The ritual was something like this. A female (I assume) tern would take off and start climbing and be quickly joined by two other terns (I assume males). She would do really intricate maneuvers- barrel rolls, inside-outs, etc. and the two pursuers tried to copy her. After several minutes of this she somehow would indicate her choice and the rejected bird would fly away. Then the couple did even more extraordinary maneuvers, diving, climbing, rolling, etc. and covering a lot of air space from the beach club out to over the Sealofts and back. They were always in perfect sync with one slightly behind and to the side of the other. It was extraordinarily beautiful, better than any ballet.

Questions: Is this standard behavior for a certain class of terns? Does it go on wherever these terns mate or is it peculiar to our coast? Which terns are these? What month are they most likely to do this?

Thanks for your feedback

Andy Allen


Without knowing which species of tern Andy saw, it is challenging to make a definitive statement. Yet, Andy did provide some useful clues with his careful observations. To start at the basics, there are five species of terns likely to breed on or near Seabrook Island: Royal Tern, Forster’s Tern, Least Tern, Sandwich Tern and Gull-billed Tern.

Two of these species, Gull-billed Tern and Least Tern, tend to make more horizontal flights during pair bonding. So, we will rule out those species.

Forster’s Terns generally nest in the marshes, so we may want to rule out the Forster’s Tern, though it is worth understanding how they interact during pair bonding. The Royal Terns and Sandwich Terns nest on Deveaux Bank.

Most species of tern perform flights called “Dreads.” This is where a whole flock lifts up and flies around, not just because of a nearby predator, but as part of pair bonding and colony cohesion. The Forster’s Tern, Royal Tern, and Sandwich Tern have courtship flights described as “High Flight.”

What I believe Andy is referring to would be the “High Flight” behavior. That leaves the three species, Royal, Forster’s and Sandwich Terns. Here is how the scientists who wrote the pages for these terns on Birds of the World describe the variation in each species “High Flight.”

Forster’s Terns – Ed Konrad

Forster’s Tern: “Two terns (sometimes 1 with fish) begin circling ascent in “jerk-flying” (Baggerman et al. 1956) manner (wings angled back with pause [jerk] at bottom of downstrokes, wing beats at faster rate [3–4 beats/s] than normal flight [2–3 beats/s]) up to 200 m. At highest point, leading tern starts gliding descent in Aerial Bent Posture (beak pointed downwards, black cap tilted away from other tern, wings held above horizontal); second tern performs Pass (gliding low over first tern) and adopts Straight Posture (beak forward, head tilted so black cap points away from other tern), initially fast and steep; Pass may be repeated. High flight may begin from ground or from flight. Terns may be silent or utter calls during Ascent. Fish-carrying tern most often the individual performing Aerial Bent Posture. After landing, if first tern was fish-carrying individual, that individual feeds the other during Posturing or Parading (see below; MKM).”

Royal Tern, Beachwalker Park, Kiawah Island – Ed Konrad

Royal Tern: In High Flight, one, presumably male, spirals upward, giving Advertising-Call, pursued by ≥1, commonly 2 individuals. During ascent, leader also gives Aack Calls, as do pursuers. Where >1 pursuer, these may pair off and continue own High Flight. Fish sometimes passed between 2 flying birds that have paired off, one dropping it a short distance to other below. Third may join and replace one of 2 original participants or cause 2 to break off aerial courtship. At peak of ascent (≥100 m), leader initiates downward glide, closely followed by pursuer. Both describe spiral descent during which Pass Ceremony may occur, as in Sandwich Tern. High Flight may last up to 25 min and lead to ground courtship, but pair more often retires to fish or to loafing flock to rest, preen, or bathe. Aerial courtship diminishes at hatching time, but occurs throughout breeding season.

Sandwich Tern, Beachwalker Park, Kiawah Island – Ed Konrad

Sandwich Tern: Usually aerial display follows ground courtship. An unmated male flies around a flock of loafing birds, usually carrying a fish and vocalizing in advertisement. He may alight on the ground near the flock and raise head and bill while calling, with wings held away from the body and crest raised. When female approaches, male takes off in an aerial “bent posture,” with head and bill pointed toward the ground and back arched. Female may or may not follow male into “high flight” display, and other birds may join in. Aerial courtship consists of ≥ 2 birds ascending in a circle for one to several minutes; at the apex, one bird breaks into a fast downward “glide,” often after several false starts. In the glide, the birds fly close together and trailing bird may overtake lead bird.

The short answer to Andy’s questions are as follows.

  1. This is a standard behavior of many tern species.
  2. It goes on wherever terns congregate.
  3. The above descriptions lead me to believe that the birds Andy refers to are Royal Terns (though his assumption is about sex is wrong) as the behavior he described more closely matches that of the Royal Tern, though Andy did not mention if the birds were noisy or not.
  4. The Forster’s and Royals are already here. The Royal Terns are pair bonding and setting up nesting territories in early April into May. The Forster’s Tern is mid-April to mid-May. The Sandwich Tern, which should be arriving in the next couple weeks, would be displaying in late-April to early-May. I do have to add that the first Least Terns, a SC Species of Concern should be arriving on Seabrook Island in about a week. Least Tern numbers grow through May. Each year, we have high hopes that a colony will once again establish itself on North Beach. Be sure to watch the antics of this species, but stay well out of their way so as not to disturb them!

One of the joys of living on or visiting Seabrook Island is being able to watch the birds and the bird behavior. We would love to hear from people who observe any of the above behaviors.


Buckley, P. A., F. G. Buckley, and S. G. Mlodinow (2021). Royal Tern (Thalasseus maximus), version 1.1. In Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.

McNicholl, M. K., P. E. Lowther, and J. A. Hall (2020). Forster’s Tern (Sterna forsteri), version 1.0. In Birds of the World (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.

Shealer, D., J. S. Liechty, A. R. Pierce, P. Pyle, and M. A. Patten (2020). Sandwich Tern (Thalasseus sandvicensis), version 1.0. In Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.

  • – Bob Mercer, SIB’s “Resident Naturalist”

Ask SIB – American Oystercatcher U5

One of our Facebook followers asked the question below:

Q: I found a photo of U5 that I took 8 years ago. How long do oystercatchers usually live?

Cindy Moore Johnson

A: We found this on the Cornell Lab of Ornithology website, All About Birds: 

“The oldest American Oystercatcher was at least 23 years, 10 months old. It had been banded as an adult in Virginia in 1989 and was found in Florida in 2012.”

As for U5, he is a popular blog subject for us. Two years ago we wrote:

“Just like the biologists, we can learn a lot from the approximately 60 resights in U5’s registry.  In December 2008, U5 was banded as an adult on Little Saint Simons Island, Georgia. According to SCDNR, he is 15 -16 years old, which is old for an American Oystercatcher!”

We all remember being so excited in 2021 when U5 & mate successfully fledged 2 chicks. Last year, they nested three times but lost their eggs to gulls & crows. Oystercatchers are formidable flyers and adversaries but their defenses can be overwhelmed by the coordinated attacks by groups of those predators especially when they are simultaneously defending their territory from other interloping pairs of oystercatchers. 

We are currently watching 3 pairs of oystercatchers who were on our beach last year as well: U5 & mate, EM & mate & a pair that is not banded. They are all trying to establish nesting territories now but unfortunately they only have half of the suitable habitat that they had last year. The current posted area is only large enough for one pair and the other pairs will be competing for whatever space is remaining. American Oystercatchers, while not officially listed as endangered or threatened, are listed as a species of concern. 

Please give these beautiful shorebirds space to rest, to nest & to eat. That means staying as far away as possible when walking on the beach. The signs are only a suggestion of the space they will need. This especially applies to photographers. Pushing in close to the signs to take a cellphone picture will only add further stress to the birds. They have stress enough now while competing with the other pairs!

If you are interested in becoming a Shorebird Steward, send us an email ( and we’ll schedule personalized training that works for you.

To learn more about American Oystercatchers, below are a few of the blogs we’ve published.

– Mark Andrews, Seabrook Island Shorebird Steward Program

IMPORTANT – Please Read

We are thrilled that so many people are excited about our nesting pair of Bald Eagles and their two young, but we must remind you that the nest is on private property. Safely walking along the street is fine, but DO NOT TRESPASS on private property including the empty lot and all property in the area.

Every day, throughout the day, numerous people are walking into the yards of our neighbors and into the woods to the bird’s nest tree. This is trespassing!  It has also been reported that this activity is stressing the birds, the last thing any of us want to happen. Please read the blog we published two weeks ago about “Ethical Birding” to remind yourself of the proper etiquette while birding and photographing wildlife.

Thank you for respecting the property of our neighbors and your safety!

What kind of Hawk is that?

You spot a hawk, but you’re not sure what kind of hawk you’re seeing. Is it a Cooper’s? A Sharp-shinned? Red-shouldered or Red-tailed?

Hawks – Birds and Bloom

If you’re out birding and listing your sightings in eBird then you definitely want to know exactly what you’re looking at, in order to correctly report your sighting. Need some help to polish your hawk identification skills?

Here’s a great article from Birds & Blooms magazine with 5 tips to help you identify hawks accurately.

Do you have photos of hawks you’d like to share with Seabrook Island Birders? Send your photos to us and we’ll share them on our Instagram and Facebook pages. Email your pics to

Happy Birding!

Article Submitted by: Gina Sanders

Shorebird Stewards: Myth Busters

In 2022, we had 19 volunteers to be Shorebird Stewards on Seabrook Island. These people spent a total of 170 hours on the beach and most importantly, interacted with 746 people. We are planning an even better year this year. If you want to be part of the fun, send an email to

Some myths/concerns were heard from earlier communications. We wanted to address these concerns:

Myth: You have to know a lot about shorebirds to participate.
Response: Stewards educate people about ways to reduce human impact on birds, not bird identification!

Myth: Shorebird Stewards will be talking to people who already know all about shorebirds.
Response: Every year new people come to the beach to see dolphins or turtles
but don’t know the shorebird story. In 2022, 66% of the people who stopped by the Shorebird Steward Station were visitors to Seabrook Island. Stewards ask beachgoers to respect the shorebirds as they are feeding in the surf or resting at the inlet by not approaching the birds too closely and by walking around them. The message- “Share the Beach-Give The Birds Space”

Myth: I need to approach people to tell them about shorebirds
Response: Shorebird Stewards are trained to respond to people who approach them rather than approaching people who are not interested.

Myth: Shorebird Stewards must enforce the Seabrook Island beach rules.
Response: The stewards program asks you to be a volunteer to help educate people about the importance of our tiny piece of the world to the shorebirds that visit. This is not an enforcement effort, but an educational effort. Contact numbers for Beach Patrol and Seabrook Island Security are available to be contacted if a need arises.

Myth: Everyone knows the yellow “sanctuary” area on North Beach is to protect the sea turtles. Why do the Shorebird Stewards set up near that area?
Response: The area within the signs varies by season and the fluctuating tides. This is a “critical habitat area”. In winter, it is a shorebird roosting area where the birds may rest and conserve energy. In summer, the area may move and is where endangered species nest on scrapes in the sand. Shorebird Stewards help educate people about these uses. Loggerhead Turtles may go into the area to nest and Seabrook Island Turtle Patrol works with the Shorebird Stewards to minimize impact to the birds while also protecting the turtle nests.

Myth: I’d have to be on the beach every day, all day
Response: Shifts are in 2 hour blocks. Each person signs up for as many (or as few) shifts as they wish.

Myth: I have to complete a lot of paperwork regarding my time as a steward
Response: Our website allows you to self-schedule your shifts and makes it very easy to complete a report of your experience after each shift.

Myth: I’d have to be by myself for my shift
Response: Usually 2 people are on the beach together. You can find your own partner or you can register as a single and another single can register to join you.

Myth: People are abrasive to the Stewards
Response: The Shorebird Stewards report that 98% of the interactions are positive. Training includes how to respond to negative people.

Myth: Only children want to talk to Shorebird Stewards
Response: 89% of the interactions were with adults but often, children bring their adults so they can all hear about the birds.

Myth: I have to have a scope to participate
Response: A scope is proved to the volunteers who wish to use it.

Myth: I have to lug a scope, signs and other equipment to the inlet to complete my shift
Response: A wagon is provided for the shorebird stewards to get their equipment to the beach. Stewards do not need to walk all the way to the inlet, they can set up anywhere between Boadwalk#1 and the inlet. The provided equipment includes signs, the scope and even a chair with an umbrella. Stewards are asked to provide their own water and sun screen.

Myth: I can’t participate as I’m only on Seabrook for part of the season
Response: Although the season is from March through May (with possibility for expansion through nesting season), you schedule to volunteer based upon your availability and when you are on Seabrook.

Myth: The Shorebird Stewards are on the beach all summer in the mid-day heat
Response: The peak season is in the spring when the Red Knots are migrating through. Therefore, the season is over before the real South Carolina heat begins.

Myth: I was unavailable on February 24 for training so I can’t be a Steward
Response: If you are still interested in becoming a Shorebird Steward, send us an email ( and we’ll schedule personalized training that works for you.

SIB “Bird of the week” – Eastern Screech Owl

Eastern Screech OwlMegascops asio
Length: 6.3-9.8 in. Weight: 4.3-8.6 oz.
Wingspan: 18.9-24 in.

If you find yourself in a wooded area at night, don’t be too alarmed if you hear a haunting whinny floating across the night air. No, it’s not a ghost horse, it’s likely coming from a bird no bigger than a pint sized glass – an Eastern Screech Owl. In fact, hearing this owl is probably easier than seeing him as they’re well camouflaged and hide out in nooks and crannies of trees during the day. Your best chance of seeing one is to keep your eyes out for smaller birds causing quite the commotion. Blue Jays, Chickadees and Titmice will often mob a screech-owl (or other raptor), swooping around it with noisy calls. This can be enough of a nuisance to the owl to make him move on, and it alerts other birds to the predator’s presence.

They have two color-morphs, rufous (reddish-brown) and gray, with the rufous coloration making up one-third, and more common in the East. No other North American owl has such distinctive plumage differences. They have small ear tufts and yellow eyes, strongly streaked upperparts and finely barred and streaked underparts, giving them their excellent camouflage.

Eastern Screech Owls are found wherever trees are, from the Rocky Mountains to Canada to Mexico. Because they readily habituate to people, Eastern Screech-Owls sometimes roost and nest in human-made cavities such as bird boxes. They nest in holes and cavities but never dig a cavity themselves. They depend on tree holes opened up and enlarged by woodpeckers, squirrels or wood rot. Because old, dead or dying trees are often removed from yards, they’re sometimes short of nest sites and have been known to nest in wood piles, mailboxes, or crates left on the ground. They’re fearless defenders of their nest and will even strike unsuspecting humans on the head as they pass nearby at night.

Eastern Screech Owl pairs are usually monogamous and remain together for life. Nesting occurs between March and June. Females incubate 3-5 eggs for 30 days, feed nestlings for nearly as long, and then tend the fledglings for 8-10 weeks. Their diet is the most varied of any North American owl, to include a variety of songbirds, mice, rats, squirrels and rabbits, and a surprisingly large number of earthworms, insects, frogs and lizards. When prey is plentiful Screech-Owls store extra food in tree holes for as long as four days.

Small but mighty, Eastern Screech-Owls are mainly active at night, though they often hunt at dawn or dusk. They sit and wait in the trees for prey to pass below, then pounce from perches six to ten feet off the ground. In addition, suburban screech-owls often survive better than their rural cousins, as suburbs provide more prey and fewer predators. Their small size, territorial tolerance, and broadly varied diet make this owl a successful survivor.

Screech Owl at Brookgreen Gardens – Susan Markum

Screech Owls are on Seabrook Island but as stated earlier, are rarely seen. A pair raised their young in a tree near the bird feeders at Camp St. Christopher several years ago. One was heard prior to a walk in the Maintenance area but wasn’t seen. Below is a picture taken on a visit to Brookgreen Gardens in February 2023.

To read more, go to:

Submitted by Gina Sanders
Photos from National Audubon Society and The Cornell Lab All About Birds

This blog post is part of a series SIB will publish on a regular basis to feature birds seen in the area, both migratory and permanent residents.  When possible we will use photographs taken by our members.    Please let us know if you have any special requests of birds you would like to learn more about.

Learning Together at Jenkins Point

To register click here!

Friday March 24, 2023  8:30 am – 10:00 am
Location:  Meet at First Lagoon on left
Max:  20
Cost: Free for members; $10 donation for guests – Priority will be given to prior waitlisted & members

We’ll be exploring the birds seen along Jenkins Point lagoons and streets, including wading birds, shorebirds, song birds and possibly ducks.  We’ll go from location to location via car or bike.  Since this event can be primarily by car, it is appropriate for members with mobility issues.  Meet at Jenkins Point Ct., the street after the first pond on the left.

As always, be sure to bring your binoculars/cameras, hats, beverage and sunscreen.

If you’re not yet a 2023 SIB member, you must first become a member for only $15 by following the instructions on our website: You may bring the form and your dues to the event. Or you may pay the Guest Fee of $10.

Final Reminder – Register for “Red Knots in the Southeast US” on March 23rd

Red Knots in the Southeast US:
Acting Locally, Thinking Globally

Speaker: Fletcher Smith, Georgia Department of Natural Resources

DATE: March 23, 2023,
LOCATION: Lake House Live Oak Hall (Max: 100)
7:00pm Registration & Refreshments
7:30pm Program
8:30pm Q&A and Program Close
COST: Free for 2023 SIB Member; $10/guest
(Learn How to join SIB)

Program Description:

For years we’ve told the remarkable story of the 9000 mile Red Knot migration, flying from Tierra del Fuego at the tip of South America to the Arctic to breed, and making an important stop at Seabrook to rest and fatten up. But did you know that many Red Knots spend entire winters in the southeastern United States along the Florida, Georgia, and South Carolina coasts, including Seabrook Island?

Please join us to hear Fletcher Smith discuss this subspecies of Red Knots that rely on the Southeast coast’s developed beaches for most of the year before flying to the Arctic, like their more famous brethren, to breed. Fletcher has been a migratory shorebird researcher for more than 20 years, working from the high Arctic to the South American wintering grounds. He is currently a wildlife biologist with Georgia Department of Natural Resources, researching and monitoring shorebird populations along the Georgia coastal islands. Through this work, he is very familiar with the Red Knots at Seabrook and Kiawah Islands. 

Fletcher will review the life cycle of Red Knots, and their breeding season and wintering ecology. His focus will be the critical linkage that Seabrook and Kiawah provide as a stopover during all Red Knot migration, and why this is so important to this threatened species.

Speaker Biography:Fletcher Smith has worked with a diversity of bird species throughout the western hemisphere, following migrants from their breeding to winter grounds. His research projects include work with Whimbrels, Red Knots, Marsh Sparrows, and neo-tropical migrants. Fletcher currently is a wildlife biologist with Georgia’s Department of Natural Resources. He holds a B.S. in Biology from Northland College in Wisconsin, a private liberal arts college with a progressive focus on the environment and sustainability.

Be sure to register so you won’t miss this exciting event!

Also, it is not too late to join or learn more about the Seabrook Island Shorebird Steward Program!  ​We invite you to visit the Seabrook Island Birders webpage ( and visit the Shorebird Stewards tab. Sign up with your spouse or a friend, or meet new friends during the upcoming training sessions. Send an email to to join the group or ask for more information. It is a rewarding experience that you will surely come to cherish.

Did you know: Birds molt changing their appearance

In mid-February, I saw a bird for the first time on Seabrook Island – an Indigo Bunting. I didn’t recognize it initially with it’s brown plumage with just a hint of blue. After about a week, it disappeared to return mid-March. Boy, what a difference now that he was in his breeding plumage. The pictures were taken through a window but they still clearly show the difference.

I know several “Yankees” who didn’t initially recognize our wintering American Goldfinch in their drab plumage. About the same time as my Indigo Bunting returned, I saw an American Goldfinch in his summer finery. These changes caused me to research more about molting. The Cornell Lab’s All About Birds site provided an excellent article: The Basics: Feather Molt. The first few paragraphs answered a lot of my questions:

A feather is a “dead” structure, analogous to hair or nails in humans and made of the same basic ingredient, the protein keratin. This means that when they get damaged, feathers can’t heal themselves—they have to be completely replaced. This replacement of all or some of the feathers is called molt. In addition to providing a new set of healthy feathers, molts often provide a new look to the bird’s plumage—new colors or patterns that can indicate the bird’s age, sex, or the season of the year.

Molt is extremely variable. Observed patterns can vary by species, by individual, from year to year, and by individual feathers on the same bird. Molts can be either complete, in which the bird replaces every one of its feathers over the same molt period; or partial, in which the bird replaces only some of its feathers (for example, flight feathers or body feathers).

Molt keeps birds in top flying condition by replacing feathers that have become worn or damaged with completely new feathers. However, if a bird loses an entire feather, that feather will begin growing back immediately rather than waiting for the next molt. (This is why people clip the flight feathers of captive birds rather than plucking them out.)

Molting occurs in response to a mixture of hormonal changes brought about by seasonal changes. The entire process is complex and many questions remain regarding how the process is controlled. A basic understanding of molting patterns can be a useful aid in identifying many species and in determining their age.

It takes a lot of energy to build new feathers. As a result, timing is important—and birds typically time their molts to avoid other periods of high energy demands, such as nesting or migration. Molt timing can be more complicated for larger birds, because growing larger feathers means that their molt process takes longer than it does for smaller birds. This is one reason why some birds undergo partial molts.

I encourage you to read more about this feature of our feathered friends but reading the entire article The Basics: Feather Molt by Cornell Lab’s All About Birds.

Submitted by: Judy Morr

Did you know” is an on-going series of blogs that answer possibly more technical questions people have about birds or their environments. If you have an idea or question, submit it via the “Ask SIB” link on the web site or send an email to

Ask SIB: What is Brown-headed Cowbird doing?

Question: Have researched this question to no avail! We have tons of Brown headed Cowbirds this time of year on the feeders and on the ground. Often a male or two puffs himself up, tucks his head in, and naps on the ground under the largest feeder. Seems like a risk with all the birds of prey around. If you approach, they are not startled very easily. Never seen this before and is it normal? Thanks for any input! – Paula Adamson

Answer: This is not a behavior that I am familiar with, but we can always hypothesize. During the winter months, the Brown-headed Cowbird is a social bird hanging around with birds of a feather and other blackbirds. If multiple birds hang around together, every bird does not need to be watchful for predators. There needs to be some paying attention. Those birds sound the alarm and the quick reaction time for a bird would allow them to avoid predators.

Brown-headed Cowbird – Dean Morr

If you had said that the birds fluffed themselves out, sat spread tail, and occasionally shook their head, I would have said the bird was anting. This common behavior lets ants roam over the birds body picking off parasites, but it usually does not look like sleeping.

About now, the Brown-headed Cowbird will start to pair up resulting in a whole host of displays, some to entice a mate others to define dominance. A bunch of males will go through an array of display postures which can be lifting their wings as they sing, fanning their tails, spreading their wings and bowing, or puffing up, arching their back and then move into a bow in an effort to entice a female. The male with the most moves will be the lucky one. Watch for some of these behaviors at your feeder.

While many birders revile the cowbird, they are a remarkable species. It is well known that these birds do not build their own nest, but lay their eggs in the nest of other birds who then raise their young. Scientist have documented 144 species that have raise cowbird eggs though they have seen cowbird eggs in the nests of over 220 species. Somehow once the baby is out of the nest, it recognizes that it is not the species of its adoptive parent. It then seeks out other cowbirds to hang out with at our feeders. Since we cannot do anything about their parasitic behavior, while we grumble about their abundance, maybe we should learn to watch and enjoy the uniqueness.

The Brown-headed Cowbird: An Abundant Brood Parasite (
Behavior – Brown-headed Cowbird – Molothrus ater – Birds of the World

– Bob Mercer, SIB’s “Resident Naturalist”

Postscript comment from Paula: Thanks so much for your input. I was mostly concerned that the sleeping cowbirds looked like a perfect target for birds of prey, and I was right. Bob was watching with binoculars the other day and a sleeping Cowbird was scooped up by a red tailed hawk and taken away. Of course, part of normal nature, but the Cowbirds maybe aren’t too smart? Happy bird watching everyone!

Bob’s response: “Predators can most easily take the weak, sick, or aged prey. Your cowbird probably fell into one of those categories. It would explain the odd behavior that you first noticed.”

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