Interior Least Terns at Hagerman NWR

Last week Dr. Wayne Meyer's Second Saturday program was on Terns, particularly the Interior Least Tern. Thirty Interior Least Terns were spotted by the birders at Hagerman National Wildlife Refuge on May 22, then only 8 on May 29 and 4 on June 5. Until this week,  no nesting activity had been reported and the question has been, will they nest here this year or have they moved on?

Now we have the answer!  From Jack Chiles Tuesday Bird Census for June 12, "The highlight of the day was discovering that the Least Terns have settled in, starting to nest."

The Refuge was ready, with two nesting platforms placed in Lake Texoma. (Photos were taken in 2015 by Rusty Daniel and Gary Hall)

Habitat for the Least Tern, as described by Cornell Lab of Ornithology on All About Birds is “Seacoasts, beaches, bays, estuaries, lagoons, lakes, and rivers, breeding on sandy or gravelly beaches and banks of rivers or lakes, rarely on flat rooftops of buildings.” You can add to that the two artificial nesting platforms at Hagerman, especially designed and built by Refuge employees for the Least Tern. Funding for the project was provided by Jetta Operating Company, Inc and the Nancy Ruth Fund.

The first of two artificial nesting platforms (above) was completed and put in place the summer of 2013.  A second platform was constructed and was to be "launched" in 2014 but those plans were on hold due to drought - there was no water in the area where the platform was to go! And for the record, the one-legged Terns in the photo above from 2013 are decoys!  BUT - once again the terns have chosen the pad roads, according to Jack, nesting "on C and D pads. Those areas have now been closed off to the public (no walking/no driving) to protect this endangered species. We counted 20 Least Terns and saw at least 4 birds sitting on eggs. One nest visible from the edge of the pad had 3 eggs. The nests will be monitored until the birds that hatch out fledge six weeks or so from now".

The Least Tern, the smallest American Tern, is an 8 to 9-inch bird, with a black "crown" on the head, a snowy whiter underside and forehead, grayish back and wings, orange legs, and a yellow bill with a black tip. Males and females are similar in their appearance. The name “Interior” is attached to Least Terns who breed in isolated areas along the Missouri, Mississippi, Ohio, Red, and Rio Grande river systems. They winter in coastal areas of Central and South America.

Interior Least Terns at HNWR, photographed by Eileen Sullivan in June, 2011

The Interior Least Tern is endangered due to loss of habitat, primarily because of changes in river systems and competition from recreational development. Terns arrive at the breeding ground in late spring – early summer and spend several months there. According to Dr. Wayne Meyer, courtship behavior includes the male showing off a fish to potential females, see photo above. Nesting in small colonies, Terns scratch out a shallow depression in sand or gravel for a nesting spot. The female lays 2 – 3 eggs in 3 – 5 days. Parents take turns incubating the eggs for about 3 weeks; Dr. Meyer says that the female does the lion share of the incubating.  Chicks hatch one per day and leave the nest a few days after hatching but continue to be fed and cared for by adults for about two months.

Nesting adults defend an area surrounding the nest (territory) against intruders. Intruders can include humans, coyotes, fox, raccoons, bobcats, domestic dogs and cats, American Crows, Great Egrets, and Great Blue Herons among other creatures. When defending a territory, the incubating bird will fly around giving an alarm call and diving repeatedly at the intruder.

Terns feed on small fish and aquatic creatures and can be seen hovering and diving for prey, as well as skimming for insects. The young have to learn these hunting skills during their "nursery" days.

Tern in flight, photographed by Mike Chiles

Terns usually return to the same nesting area year after year. Before the launch of Tern Island I and II, the birds chose the rocky surface of the pad roads for their nursery, completely vulnerable to predators and extreme summer heat; the successful hatch rate was low to none. However, they still had not taken to the presumably safer man-made nesting platforms in 2017; they produced 10 eggs and 5 live chicks, on the pad roads C and D.

Nesting Tern, photographed by Jack Chiles in 2011 on one of the Pad roads at HNWR.

Hopefully, the terns will have a successful hatch this year.


Thanks to Jack Chiles, Texas Master Naturalist, for the original post on Least Terns, July 13, 2011.  Material has been updated in 2015, 2017 and 2018. In addition to All About Birds, information for this post came from Texas Parks Wildlife and from US Fish & Wildlife.

Interior Least Terns

If you have visited Hagerman National Wildlife Refuge in the last week you have probably noticed that C Pad and D Pad are barricaded. These pads are sites that the Least Terns have chosen to build their nests. The Interior Least Tern is an endangered species due to loss of habitat and is protected by Federal Regulations.

According to Paul Balkenbush, HNWR Deputy Manager, on July 5, 2017, "We observed about 24 adults foraging and loafing including 16 on C Pad and 8 on D Pad. There was some transfer between pads so a total count was challenging. We also observed three ILT nests (one on C Pad and two on D Pad) but there could have been more. We did not venture close enough to be certain because of the potential of stepping on eggs. Both C and D pads are protected from traffic via barricades. I plan to take another look tomorrow to see if there is ILT activity on other pads that need to be protected."

Nesting Tern, 2011, by Jack Chiles

The Least Tern is the smallest of the North American terns. The breeding adult is gray above, with a black head and nape and with black extending from the eye to the bill. It has a white forehead and an orange-yellow bill with a dark tip. The underparts are white and the legs orange-yellow. In flight look for the black wedge on the outer primaries (the outermost wing feathers) and the short deeply forked tail. An average adult is 8 to 10 inches in length and has a 20-inch wingspan.

Interior Least Terns usually begin nesting here in late May or early June preceded by 2 to 3 weeks of noisy courtship. This includes finding a mate, selecting a nest site, and strengthening the pair bond. Courtship often includes the “fish flight”, an aerial display involving aerobatics and pursuit, ending in a fish transfer on the ground between two displaying birds. Courtship behaviors also include nest preparation and a variety of postures and vocalizations. Least Terns are colony nesters where nests can be as close as 10 feet apart but often are more than 30 feet apart. The nest that you usually see here is a very shallow depression in the gravel.

The terns are late this year. Egg-laying usually begins in late May with the female laying 2 to 3 eggs over a period of 3 to 5 days which are then incubated, with the male and female alternately sharing duties for a period of about 21 days. The eggs are pale to olive buff and speckled or streaked with dark purplish-brown, chocolate or blue-gray markings.

Nesting adults defend an area surrounding the nest (territory) against intruders. Intruders can include humans, coyotes, fox, raccoons, bobcats, domestic dogs and cats, American Crows, Great Egrets, and Great Blue Herons among other creatures. When defending a territory, the incubating bird will fly around giving an alarm call and diving repeatedly at the intruder.

Where's Waldo?  Find the Tern chick in this photo, taken in 2009 by Dick Malnory

The chicks hatch within one day of each other and remain in the nest for about a week. Then they will wander from the nest in search of shade or cover. They will be able to fly within 3 weeks of hatching.

For feeding the Least Terns need shallow water like we have at Hagerman NWR which provides an abundance of small fish.

Tern parent with chick, 2011, by Eileen Sullivan

In an effort to help the terns successfully raise their young we monitor the terns a minimum of once a week during the nesting season. We try to locate all the nests and map them out. Then we keep records of eggs laid, eggs successfully hatched and birds that fledge. 

For 2017, two artificial "Tern Islands" have been placed in the lake near the pads off Oilfield Roads, but so far they have not accepted them for nesting places.  Balkenbush says"No terns were observed on the nesting platforms or showing any interest in them. I am concerned that the newly-added cross wires (to deter predators) might be making the artificial habitat less desirable. I am considering removing the cross wires from at least one platform tomorrow to see if it makes a difference. We will also put out some decoys on both. Seems like a good opportunity for an experiment."

Tern Island I, 2015

The Least Terns will probably be observed around the pads until late August. After the Least Terns leave in late summer we will be anxiously awaiting their return next spring as they usually return to the same breeding site year after year.

Interior Least Tern in Flight, 2011, by Laurie Sheppard

Text by Jack Chiles, Texas Master Naturalist, originally published on July 13,  2011, updated for July, 2017 by the editor.

For information about the Friends of Hagerman, see http://www.friendsofhagerman.com.

One Good Tern...

Three pairs of interior least terns were seen on the nesting platforms near the C and D Pad Roads area at Hagerman National Wildlife Refuge  this month.  Maybe the courtship behavior (offering a minnow) in one of the photos is a sign of good things to come! 

Last week, Rusty Daniel confirmed at least two nests with one egg each that were being incubated.

Thanks to Rusty  and to Gary Hall for checking on the platforms and getting these  photos to share.

Habitat for the Least Tern, as described by Cornell Lab of Ornithology on All About Birds is “Seacoasts, beaches, bays, estuaries, lagoons, lakes and rivers, breeding on sandy or gravelly beaches and banks of rivers or lakes, rarely on flat rooftops of buildings.” You can add to that the  two artificial nesting platforms at Hagerman National Wildlife Refuge, especially designed and built by Refuge employees for the Least Tern. Funding for the project was provided by Jetta Operating Company, Inc and the Nancy Ruth Fund.

The first of two artificial nesting platforms (above) was  completed and put in place the summer of 2013.  A second platform was constructed and was to be "launched" in 2014 but those plans were on hold due to drought - there was no water in the area where the platform was to go! And for the record, the one-legged Terns are in this photo from 2013 are decoys!

Tern decoy carved by Dick Malnory

The Least Tern, the smallest American Tern, is an 8 to 9 inch bird, with a black "crown" on the head, a snowy whiter underside and forehead, grayish back and wings, orange legs, and a yellow bill with a black tip. Males and females are similar in their appearance. The name “Interior” is attached to Least Terns who breed in isolated areas along the Missouri, Mississippi, Ohio, Red, and Rio Grande river systems. They winter in coastal areas of Central and South America.

Interior Least Terns at HNWR, photographed by Eileen Sullivan in June, 2011

The Interior Least Tern is endangered due to loss of habitat, primarily because of changes in river systems and competition from recreational development. Terns arrive at the breeding ground in late spring – early summer and spend several months there. Nesting in small colonies, Terns scratch out a shallow depression in sand or gravel for a nesting spot. The female lays 2 – 3 eggs in 3 – 5 days. Both parents take turns incubating the eggs for about 3 weeks. Chicks hatch one per day and leave the nest a few days after hatching but continue to be fed and cared for by adults.

Terns feed on small fish and aquatic creatures and can be seen hovering and diving for prey, as well as skimming for insects.

Tern in flight, photographed by Mike Chiles

Terns usually return to the same nesting area year after year. Before the launch of Tern Island I and II, the birds chose the rocky surface of the Pad roads for their nursery, completely vulnerable to predators and extreme summer heat; the successful hatch rate was low to none.  

Nesting Tern, photographed  by Jack Chiles in 2011 on one of the Pad roads at HNWR.

Hopefully,  the platforms at the Refuge will provide a safe nursery environment for a successful hatch this year.


In addition to All About Birds, information for this post came from Texas Parks & Wildlife and from US Fish & Wildlife.

Terns Welcome on Isle One

Habitat for the Least Tern,  as described by Cornell Lab of Ornithology on All About Birds is “Seacoasts, beaches, bays, estuaries, lagoons, lakes and rivers, breeding on sandy or gravelly beaches and banks of rivers or lakes, rarely on flat rooftops of buildings.”  You can add to that the first of two artificial nesting platforms at Hagerman National Wildlife Refuge, especially designed and built by Refuge employees for the Least Tern.  Funding for the project was provided by Jetta Operating Company, Inc and the Nancy Ruth Fund.

The first of two artificial nesting platforms has been completed and  is in place.

The Least Tern, the smallest American Tern, is an 8 to 9 inch bird, with a black "crown" on the head, a snowy whiter underside and forehead, grayish back and wings, orange legs, and a yellow bill with a black tip.  Males and females are similar in their appearance.  The name “Interior” is attached to Least Terns who breed in isolated areas along the Missouri, Mississippi, Ohio, Red, and Rio Grande river systems.  They  winter in coastal areas of Central and South America.

Interior Least Terns at HNWR, photographed by Eileen Sullivan in June, 2011

The Interior Least Tern is endangered due to loss of habitat, primarily because of changes in river systems and competition from recreational development. Terns arrive at the breeding ground in late spring – early summer and spend several months there.  Nesting in small colonies, Terns scratch out a shallow depression in sand or gravel for a nesting spot.  The female lays 2 – 3 eggs in  3 – 5 days.  Both parents take turns incubating the eggs for about 3 weeks. Chicks hatch one per day and leave the nest a few days after hatching but continue to be fed and cared for by adults.

Tern with chick, photographed at HNWR in 2009 by Dick Malnory

Terns feed on small fish and aquatic creatures and can be seen hovering and diving for prey, as well as skimming for insects.

Tern in flight, photographed by Mike Chiles

Terns usually return to the same nesting area year after year.  Hopefully the new platform at the Refuge will provide a safe nursery environment for a successful hatch this year.  At least two Terns have been photographed on the platform, to date.  For those who wish to check it out, the platform is located between “C” and “D” Pads.  And for the record, the one-legged Terns are decoys!

Nesting Tern, photographed at HNWR by Jack Chiles in 2011.

In addition to All About Birds, information for this post came from Texas Parks & Wildlife and from US Fish & Wildlife.

Nesting Least Terns at Hagerman NWR

If you have visited Hagerman NWR in the last few weeks you have probably noticed that several of the pads (Tern Pad, “D” Pad, and “F” Pad at present) are barricaded. These pads are sites that the Least Terns have chosen to build their nests. The Interior Least Tern is an endangered species and is protected in Texas by Federal Regulations.

The Least Tern is the smallest of the North American terns. The breeding adult is gray above, with a black head and nape and with black extending from the eye to the bill. It has a white fore-head and an orange-yellow bill with a dark tip. The under parts are white and the legs orange-yellow. In flight look for the black wedge on the outer primaries (the outermost wing feathers) and the short deeply forked tail. An average adult is 8 to 10 inches in length and has a 20 inch wingspan.

Interior Least Terns usually begin nesting here in late May or early June preceded by 2 to 3 weeks of noisy courtship. This includes finding a mate, selecting a nest site, and strengthening the pair bond. Courtship often includes the “fish flight”, an aerial display involving aerobatics and pursuit, ending in a fish transfer on the ground between two displaying birds. Courtship behaviors also include nest preparation and a variety of postures and vocalizations. Least Terns are colony nesters where nests can be as close as 10 feet apart but often are more than 30 feet apart. The nest that you usually see here is a very shallow depression in the gravel.

Egg-laying usually begins in late May with the female laying 2 to 3 eggs over a period of 3 to 5 days which are then incubated with the male and female alternately sharing duties for a period of about 21 days. The eggs are pale to olive buff and speckled or streaked with dark purplish-brown, chocolate or blue-gray markings.

Nesting adults defend an area surrounding the nest (territory) against intruders. Intruders can include humans, coyotes, fox, raccoons, bobcats, domestic dogs and cats, American Crows, Great Egrets, and Great Blue Herons among other creatures. When defending a territory, the incubating bird will fly around giving an alarm call and diving repeatedly at the intruder.

The chicks hatch within one day of each other and remain in the nest for about a week. Then they will wander from the nest in search of shade or cover. They will be able to fly within 3 weeks of hatching.

For feeding the Least Terns need shallow water like we have at Hagerman NWR which provides an abundance of small fish.

In an effort to help the terns be successful in raising their young we monitor the terns a minimum of once a week during the nesting season. We try to locate all the nests and map them out. Then we keep records of eggs laid, eggs successfully hatched and birds that fledge. We have cameras at each colony monitoring for problems such as varmints enabling us to possibly head off future problems. We put out logs and driftwood for shade.

The Least Terns will probably be observed around the pads until late August. After the Least Terns leave in late summer we will be anxiously awaiting their return next spring as they usually return to the same breeding site year after year.

Text and photo by Jack Chiles.

For more information about Hagerman National Wildlife Refuge,the official website is http://www.fws.gov/southwest/refuges/texas/hagerman/index.html

For information about the Friends of Hagerman, see http://www.friendsofhagerman.com.