Note: The following data are preliminary and may change upon further review.

Colony Counts

Rice Island & Other Upper Estuary Islands

The high and low on-colony counts for the week on Rice Island were on May 5th (4,127 terns) and May 3rd (1,700 terns), respectively. The Rice Island tern colony seems to be stabilizing in size based on the comparison of the weekly average colony counts over the past two weeks (see Seasonal Trends). However, in the short term (past three days) the colony has declined by nearly 50% from the high count on May 5th. Recent declines in the number of terns counted on the Rice Island colony are likely due to the high incidence of egg predation and kleptoparasitism (i.e., stealing of fish from terns) by gulls. The Rice Island tern colony may decline further if gull predation on tern eggs continues at current rates. Terns that are unsuccessful in their first nesting attempt at Rice Island may re-nest at East Sand Island, behavior that we documented last year.

No terns have been observed nesting at other off-colony areas on Rice Island (i.e., East Ridge) or on 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 May 7th (16,768 terns) and May 2nd (9,270 terns), respectively. The colony counts have increased by roughly 80% during the last week. Gull kleptoparasitism and predation rates on tern eggs on the East Sand Island tern colony continue to be very low, due in part to our gull control activities (see below). Currently, 89% of the total number of terns counted on both the Rice Island and East Sand Island colonies are on East Sand Island.

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 Thursday (5/4) and Sunday (5/7). On the first flight, 20 terns were observed roosting below the high tide line at Cate Island in Grays Harbor. This was the single largest aggregation of terns observed at any location in Willapa Bay or Grays Harbor this past week. At this time it does not appear that terns are nesting anywhere in Willapa Bay or Grays Harbor.

Upriver Sites (Three Mile Canyon and Crescent Islands)

We have observed no color-banded terns from Rice Island on either the Crescent or Three Mile Canyon island tern colonies.

Diet Composition

For the week (1 - 7 May), 79% of the identifiable fish delivered to East Sand Island (N = 328) were salmonids, compared to 92% at Rice Island (N = 360). Year to date, 65% of the identifiable fish delivered to East Sand Island (N = 1,175) were salmonids, compared to 91% at Rice Island (N = 808).

Off-Colony Distribution

Banding and Radio-Tagging

Banding and radio-tagging of adult terns on Rice Island was completed on April 15th and no additional banding or tagging is planned for terns at that colony. We intend to band and radio-tag 30 - 40 breeding terns at the East Sand Island colony during late incubation, roughly 1 - 2 weeks from now.

Radio-Tracking & Resightings of Banded Birds

During radio-tracking flights on Thursday (5/4) and Sunday (5/7), a total of 45 and 46 radio-tagged terns (out of a total of 50 terns radio-tagged at Rice Island) were detected, respectively. Similar to last week, most observations of radio-tagged terns during the flights were either on the Rice Island or East Sand Island colonies (96%). Of the four off-colony detections of radio-tagged terns this past week, 2 detections were in the upper estuary, 1 detection was in the lower estuary, and 1 detection was 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). Year to date, 22 off-colony detections (45%) were in the upper estuary, 13 off-colony detections (27%) were in the lower estuary, and 14 off-colony detections (28%) were outside the estuary. Based on data from fixed telemetry receiving stations on Rice and East Sand islands, we believe there are 17 radio-tagged terns nesting on Rice Island and 17 radio-tagged terns nesting on East Sand Island. Compared to last week, the number of terns believed to be nesting on Rice Island this week is unchanged, and the number of terns believed to be nesting on East Sand Island increased from 9 to 17 (89% increase).

This week, as many as 93 color-banded terns were observed at one time on the East Sand Island colony, compared to as many as 46 observed at one time on the Rice Island colony. Again, this represents an increase in the number of banded tern sightings on East Sand Island colony from last week to this week (74 and 93, respectively), whereas the number of banded terns counted on the Rice Island colony was similar to last week (42 and 46, respectively).

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 at the East Sand Island tern colony to enhance prospects for tern colony restoration at that site. Nine gulls were shot this week at East Sand Island. So far this season, 19 gulls have been shot on the East Sand Island tern colony.

Tern Hazing

There will be no tern hazing at the Rice Island tern colony in 2000.

Media and Other Visitors

We had visitors on East Sand Island on Thursday, Friday, and Saturday (May 4 - 6). On Thursday, Kristy Harger (teacher) and four students from the Future Farmers of America visited. This group had assisted us in making noose mats used to capture adult terns at the nest for radio-tagging. On Friday, Tara Zimmerman (USFWS), Cat Brown (USFWS), Deborah Jaques (USFWS), Al Clark (USFWS), Dave Pitkin (USFWS), Tami Tate-Hall (USFWS), Ed Wickersham (USWFW), Ray Rainbolt (ODFW), and Geoff Dorsey (USACE) met on East Sand Island to review research protocols for the East Sand Island cormorant colony and measures to prevent disturbance of listed Brown Pelicans that use the island as a roost later in the season (June - August). On Saturday, Mike and Margie Wilhelm (freelance photographers) visited.