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 April 29th (3,734 terns) and April 28th (1,570 terns), respectively. The big increase in terns on the Rice Island colony this week was partly due to an increase in the area occupied by terns. On April 28th, some fencing broke loose in high winds and knocked over some posts with flagging that had been erected in late March to concentrate roosting terns in the vicinity of the rocket nets. Once the posts with flagging were knocked over, terns quickly moved into the new area and began digging scrapes. The new area (roughly 1/8 of an acre) is continuous with the other part of the core area where terns are nesting, and up to 600 terns have been counted in this new area.

The first Caspian tern egg was spotted on the Rice Island colony in the evening of April 27th. Since then, researchers have spotted numerous nests with eggs and suspect that currently there are more than 300 eggs on the Rice Island colony. As directed by the Department of Justice, we will not venture onto the colony to conduct an egg count at the Rice Island colony until the temporary restraining order is lifted (see below). Gull kleptoparasitism (i.e., stealing of fish from terns) and predation rates on tern eggs on the Rice Island colony are extremely high.

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 April 29th (13,844 terns) and April 25th (3,764 terns), respectively. For the past two days, both morning and evening counts of terns on the East Sand Island colony have been over 12,000 birds.

The first eggs were spotted on the East Sand Island colony on April 27th, with some nests having more than one egg. We expect that the first egg was laid on East Sand on April 24th or 25th. Currently, there are hundreds of eggs on the East Sand Island tern colony. Gull kleptoparasitism (i.e., stealing of fish from terns) and predation rates on tern eggs on the East Sand Island tern colony are low to non-existent, due in part to our gull control activities (see below).

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 Wednesday (4/26) and Saturday (4/29). Fewer terns were spotted roosting in Willapa Bay and Grays Harbor this week, as compared to last week, with most islands not having any roosting terns. No terns have been observed on Cate Island in Grays Harbor since Monday, April 17th. 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)

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 (24 - 30 April), 72% of the identifiable fish delivered to East Sand Island (N = 301) were salmonids, compared to 87% at Rice Island (N = 306). Year to date, 61% of the identifiable fish delivered to East Sand Island (N = 847) were salmonids, compared to 90% at Rice Island (N = 448).

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 2 - 3 weeks from now.

Radio-Tracking & Resightings of Banded Birds

During both radio-tracking flights on Wednesday (4/26) and Saturday (4/29), a total of 46 radio-tagged terns (out of a total of 50 terns radio-tagged at Rice Island) were detected. To date, one tern has gone undetected since release and another tern was inadvertently shot during diet sampling. The other two terns not detected during radio-tracking flights were detected by the fixed receivers on colony. Only 13 out of a total of 92 detections (14%) during radio-tracking flights were off-colony; the remainder were either on the East Sand or Rice island colonies. Of the total off-colony detections of radio-tagged terns this week, 5 detections (38%) were in the upper estuary, 3 detections (23%) were in the lower estuary, and 5 detections (38%) 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). Of the 5 detections of radio-tagged terns outside the estuary this week, 3 were from Willapa Bay and 2 were from Grays Harbor. Year to date, 20 off-colony detections (44%) were in the upper estuary, 12 off-colony detections (27%) were in the lower estuary, and 13 off-colony detections (29%) were outside the estuary. This week, there were 33 detections of radio-tagged terns on Rice Island (42%) and 46 detections on East Sand Island (58%).

As many as 74 color-banded terns were observed at one time on the East Sand Island colony, compared to as many as 42 observed at one time on the Rice Island colony.

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. Five gulls were shot this week at East Sand Island. So far this season, 10 gulls have been shot on the East Sand Island tern colony.

Tern Hazing

The temporary restraining order was left in place by the 9th Circuit Court of Appeals in San Francisco on Friday (April 28th). We have been told that this will prohibit any hazing of Caspian terns attempting to nest on Rice Island in the year 2000. This is having some impact on our research and monitoring activities on Rice Island as we have been told not to enter the colony to collect data that we normally collect at this time of year (e.g., clutch size, laying chronology). Also, we cannot go on the colony to set out plots for monitoring productivity and correcting census counts from aerial photos for non-nesting terns on the colony.

Media and Other Visitors

Paul Englemeyer (National Audubon), Dan Hanson (Spokane Spokesman Review), and Mike Wilhelm (Spokane Spokesman Review) visited the tern colonies on Rice and East Sand islands on Sunday, April 30th.