What in Sandhill is going on?
They are the talk of the local birding world. Sandhill cranes are returning to Ladd Marsh this spring.
Excited birders are reaching for their binocular.
Biologist Cathy Nowak is reaching for her radio.
Nowak is assisting with a study aimed at piecing together the travel itineraries of sandhill cranes, including those returning to Ladd Marsh.The Oregon Department of Fish and Wildlife biologist is helping the International Crane Foundation monitor locations of sandhill cranes that had small radio transmitters and color markers attached to their upper legs. The radios were put on as part of a migration study funded by the foundation.
A total of 65 greater and lesser sandhill cranes had color-coded radios attached over the past year in California, Oregon and Alaska. Biologists from California to Alaska are now listening for these cranes with radio transmitters. Each transmitter has a different frequency so when one is detected biologists can easily identify the bird.
Nowak is listening for any of the 65 sandhill cranes, particularly six that had transmitters placed on them at Ladd Marsh in 2008.
Nowak monitors a radio receiver that scans for the different frequencies of the transmitters attached to the cranes. The scanner can detect signals from the birds’ transmitters on the ground from 1.5 to 2 miles.
This month, Nowak has detected radio signals from four sandhill cranes, all which had transmitters attached at Ladd Marsh on April 11, 2008. Nowak feels exhilaration each time she detects a new radio signal from one of the cranes she helped put a transmitter on.
“It’s as if you have a friend out there. It’s like seeing someone you know,’’ Nowak said.
Findings of biologists participating in the study indicate that the sandhill cranes that had radios attached at Ladd Marsh are bound for Alaska where they will nest. These birds apparently look upon Ladd Marsh as a “getaway’’ from the rigors of air travel.
“This is an important area to rest and feed,’’ Nowak said.
The adult birds stay for less time than the younger birds. This is probably because the adult birds are more likely to have a mate and thus eager to reach their nesting site in Alaska.
“They have a greater sense of urgency,’’ Nowak said.
The cranes to which transmitters were attached at Ladd Marsh were captured last spring with a rocket net gun. The device fired a large net that fell over six sandhill cranes at one time. The birds’ heads were then covered to calm them. Color-coded transmitters and markers were attached to their legs.
Study results indicate that most of these cranes will migrate, in the fall, from Alaska to California’s Central Valley where they will winter.
No lesser sandhills nest at Ladd Marsh, but greater sandhill cranes do. Last spring, 13 pairs of greater sandhill cranes nested at Ladd Marsh. This is noteworthy because in the 1970s no sandhill cranes nested at the marsh. Greater sandhill cranes started nesting at Ladd Marsh in the 1980s after more habitat they prefer for nesting was added.
Greater sandhills, as stands to reason, are larger than lesser sandhill cranes.
The window biologists have to closely follow the routes of the sandhill cranes they are studying is relatively small. The reason is the batteries in their transmitters have a life of only about two years.
The demise of the batteries, though, will not mean biologists will no longer be able to monitor the birds. Each crane’s tag and radio has a unique combination of color markers. Biologists spotting the color-coded birds will thus be able to record some of their movements.
The public can assist with the study by reporting color-coded cranes they see. Anyone who sees a marked crane is encouraged to record the positions of the colors on each leg — plus the date, time and location — and report them to Nowak by calling 963-4954. Nowak will pass on reports she receives to Gary Ivey, western crane conservation manager for the International Crane Foundation. Ivey, who is based in Central Oregon, is leading the sandhill crane radio study.
At Ladd Marsh, sandhill cranes will likely continue arriving through April, Nowak said. Last week Nowak counted 110 on the marsh in one day. In 2008 the most she saw there was about 300 on a single day in early April.
Cranes now at Ladd Marsh will in most cases stay only a few weeks before leaving. In 2008, five of the six lesser sandhill cranes to which radios were attached on April 11 had left by April 23.
One crane with a new radio stayed at Ladd Marsh until May 29.
Why did it remain so much longer?
Mother Nature may forever keep this a small but delightful mystery.