Rice Island & Other Upper Estuary Islands

The high and low on-colony counts for the week on Rice Island were on April 23rd (1,905 terns) and April 17th (0 terns), respectively. After the decoys and sound system were removed from the colony site at the completion of the rocket netting (4/15, see previous weekly report) it took three days for the terns to return to the colony area. Since then the colony has been rapidly building in size from 389 terns on 4/18 to 1,905 terns on 4/23. Once terns began moving back into the colony area, the terns that had been roosting on the East Ridge moved further west to the ridgeline, within view of the colony area. Prior to this move, some scrape digging was observed on the East Ridge. Terns now roosting on the ridgeline do not seem interested in nesting there, as evidenced by the absence of nesting behaviors at that site. Nesting behaviors (i.e., scrape digging, courtship feeding, and copulation) are increasing in intensity at the colony site on Rice Island. We expect that egg-laying on the Rice Island colony site will begin within a week. Laying began last year on the Rice Island colony on 30 April, and this year the nesting chronology seems slightly advanced over last year. No terns have been observed either roosting or nesting at other upper estuary islands (i.e., Miller Sands Spit and Pillar Rock Sands).

East Sand Island

The high and low on-colony counts for the week on East Sand Island were on April 22nd (6,857 terns) and April 17th (1,012 terns), respectively. The evening and morning on-colony counts at East Sand Island increased throughout the week, increasing by 177% and 65%, respectively. Terns are actively digging scrapes, courtship feeding, and copulating at the East Sand Island colony site. No tern eggs have been observed on East Sand Island to date.

Coastal Sites

Aerial surveys of terns roosting and/or nesting at coastal Washington sites (i.e., Willapa Bay and Grays Harbor) were carried out on Monday (4/17) and Friday (4/21). In Willapa Bay, a total of 400 terns were observed roosting below high tide line at various locations. In Grays Harbor, 200 and 0 terns were observed roosting below the high tide line at Cate Island on Monday and Friday, respectively. At this time it does not appear that terns are nesting anywhere within Willapa Bay or Grays Harbor.

Upriver Sites (Three Mile Canyon and Crescent Islands)

Egg-laying began on the Crescent Island Caspian tern colony on or about 17 April. No tern eggs have been observed at the Three Mile Canyon Island tern colony. Egg-laying usually begins one to two weeks earlier at upriver tern colonies, compared to the estuary colonies. We have observed no color-banded birds from Rice Island on either the Crescent or Three Mile Canyon island tern colonies.

Diet Composition

For the week (17 - 23 April), 53% of the identifiable fish delivered to East Sand Island (N = 350) were salmonids. Bill load identifications were not carried out this week at Rice Island due to a lack of birds on the colony and scheduling conflicts. Collection of these data at Rice Island will resume next week and will be carried out as long as there are terns at the colony site. Year to date, 55% of the identifiable fish delivered to East Sand Island (N = 546) were salmonids, compared to 92% at Rice Island (N = 142).

Off-Colony Distribution

Banding and Radio-Tagging

Banding and radio-tagging of adult terns on Rice Island was completed last week and no additional banding or tagging is planned for terns at that site. We intend to band and radio-tag 30 - 40 breeding terns at the East Sand Island colony during late incubation, roughly 3 - 4 weeks from now.

Radio-Tracking & Resightings of Banded Birds

During the aerial flights on Monday (4/17) and Friday (4/21), a total of 40 and 42 radio-tagged terns (out of a total of 50 terns radio-tagged at Rice Island) were detected, respectively. To date, four radio-tagged terns have gone undetected. Of the total off-colony detections of radio-tagged terns this week, 15 (47%) detections were in the upper estuary, 9 (28%) detections were in the lower estuary, and 8 (25%) detections were outside the estuary. (Note: The Astoria Bridge is the dividing line between what we call the lower and upper estuary in these reports -see map ). On-colony detections of radio-tagged terns were roughly equal between Rice (26 detections) and East Sand (22 detections) islands. On Monday, 4 and 3 radio-tagged terns were detected in Grays Harbor and Willapa Bay, respectively. On Friday, there were no detections of radio-tagged terns in either Grays Harbor or Willapa Bay.

Color-banded terns have been resighted at the Rice (225) and East Sand (100's) island tern colonies this week. At least three different color-banded terns have been resighted at a mainland Caspian tern colony at the ASARCO industrial site in Commencement Bay near Tacoma, Washington. This colony is being monitored by the Washington Department of Fish and Wildlife.

Gull and Predator Control

There have been no signs of mammalian predators on either Rice or East Sand islands. Limited gull control is being carried out on East Sand Island to enhance prospects for tern colony restoration at that site. No gulls were shot this week at East Sand Island due to a lack of gull activity at the colony site. For the season, 5 gulls have been shot on the East Sand Island tern colony.

Tern Hazing

The temporary restraining order imposed by the U.S. District Court in Seattle was in place all this past week. This TRO forbids hazing of Caspian terns attempting to nest on Rice Island. The barge being used as a staging area by the Corps' contractors was removed from Rice Island on Monday, April 17. Late last week the Department of Justice, who is handling the case for the Corps of Engineers, elevated the case to the 9th Circuit Court of Appeals in San Francisco. Justice hopes to have a hearing on the TRO before the end of this week, and a decision from the 9th Circuit on whether the TRO will remain in place by Friday, 28 April.

Last year the first egg was laid by a tern on Rice Island on 30 April, and we estimate that more than 300 eggs were on the Rice Island colony by 5 May. Nesting chronology this year may be slightly advanced over last year, due to the sunny weather we've experienced until recently. Although we are confident that no eggs have yet been laid by terns on either Rice or East Sand islands, we may see the first eggs by late this week, and there may be more than 300 eggs on both islands by early next week.

The research group still has two island monitors (Ian Rose and Jason Wolf) stationed on Rice Island to monitor (1) the number of terns using the Rice Island colony site and nearby roosting areas, (2) the timing of nesting events on the tern colony, (3) the diet composition of terns attempting to nest on Rice Island, and (4) potential appearance of introduced mammalian predators on the island. They have orders from the Department of Justice to avoid any disturbance to terns roosting either on- or off-colony. There is also an order from Justice not to remove either silt fencing or flagging tape that was placed in the core colony area this year prior to the arrival of terns in order to facilitate the rocket netting. At the time of writing, we are waiting for authorization from Justice to remove any mammalian predators that might be released on Rice Island. No introduced predators have been detected so far on Rice Island.

Media and Other Visitors

There were no visitors in the field this week.