A partnership between Oregon State University, Real Time Research, and the USGS - Oregon Cooperative Fish and Wildlife Research Unit

Columbia River Estuary

Weekly Update for 5/16 – 5/22/2016

5/16 – 5/22/16 ›

High count for the week of an estimated 6,550 individual Caspian terns on the East Sand Island tern colony, similar to the estimated high count of about 6,400 terns for the previous week; based on counts so far this year and counts in previous years, we have likely reached the peak number of Caspian terns on the East Sand Island colony in 2016; egg-laying by terns on-colony continued, with a few nests containing four eggs (normal clutch size = 1-3 eggs); egg depredation rates by gulls around the periphery of the tern colony remains high, usually associated with bald eagle disturbances to the tern colony that cause terns to flush from their nests; one Caspian tern that was satellite-tagged at the colony on Crescent Island in the Columbia Plateau region in 2015 was resighted attending an empty nest on the East Sand Island tern colony

5/16 – 5/22/16 ›

Monitoring continued at Caspian tern nest dissuasion areas on the east end of East Sand Island, outside the 1-acre designated Caspian tern nesting area; 20 tern eggs were discovered just outside the passive dissuasion on the south and southeast beaches, and all were apparently depredated by gulls within three hours of discovery; regular hazing (nearly continuous from 0530 to 2130) is being conducted in an attempt to prevent the formation of satellite tern colonies on the upper beach just south and southeast of the main Caspian tern colony; at week’s end there were no active Caspian tern nests containing eggs at either location; total number of terns observed loafing on the beaches surrounding the 1-acre nesting area was 400-1,000 individuals this week, slightly fewer compared to the previous week (500-1,500 individuals) 

5/16 – 5/22/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony continued, causing terns to frequently flush from the colony and exposing tern eggs to gull predation; eagles were also observed stealing fish from terns returning to the colony to feed their mates

5/20/16 ›

First boat-based survey of roosting California brown pelicans conducted at East Sand Island this season; a total of 250 brown pelicans counted throughout the island, nearly all on the southeast beach at the east end of the island, near the Caspian tern colony; the previous day (5/19), as many as 1,050 brown pelicans were counted on the beach near the tern colony at around mid-day

Weekly Update for 5/9 – 5/15/2016

5/9 – 5/15/16 ›

High count for the week of an estimated 6,400 Caspian terns on East Sand Island tern colony, up slightly from the estimated high count of about 6,100 terns for the previous week; egg-laying by terns on-colony continued, with many nests now containing multiple eggs; egg depredation rates by gulls around the periphery of the tern colony remains high, usually associated with bald eagle disturbances to the tern colony that cause terns to flush from their nests; one Caspian tern that was satellite-tagged at the colony on Crescent Island in the Columbia Plateau region in 2015 was resighted attending an empty nest on the East Sand Island tern colony

5/9 – 5/15/16 ›

Monitoring continued at Caspian tern nest dissuasion areas on the east end of East Sand Island, outside the 1-acre designated Caspian tern nesting area; this week additional passive nest dissuasion materials (stakes, rope, and flagging) were added to sites on the south and southeast beaches where Caspian terns had been prospecting for nest sites; one tern egg was laid just outside the passive dissuasion on the south beach, only to be depredated by a gull three hours later; as many as 22 Caspian tern nests scrapes were counted on the upper south beach; regular hazing (nearly continuous from 0530 to 2130) is being conducted in an attempt to prevent the formation of satellite tern colonies on the upper beach just south and southeast of the main Caspian tern colony; 500-1,500 terns have been loafing on these beaches, but at week’s end there were no active Caspian tern nests containing eggs at either location

5/9 – 5/15/15 ›

High count for the week of an estimated 590 California brown pelicans loafing on the southeast beach near the Caspian tern colony on East Sand Island; island-wide surveys for brown pelicans are scheduled for next week; no brown pelicans have been observed in upland areas on East Sand Island so far this season

5/9 – 5/15/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony continued, causing terns to frequently flush from the colony and exposing tern eggs to gull predation; eagles were also observed stealing fish from terns returning to the colony to feed their mates; several colony-wide flushes occurred after dusk and just before dawn on 13-14 May, believed to be caused by a great horned owl; fresh river otter tracks regularly seen on the north beach

Weekly Update for 5/2 – 5/8/2016

5/2 – 5/8/16 ›

High count for the week of an estimated 6,100 Caspian terns on East Sand Island tern colony, up from the estimated high count of about 5,000 terns for the previous week; egg-laying by terns on-colony has intensified, with many nests now containing multiple eggs; egg depredation rates by gulls around the periphery of the tern colony is high, usually associated with bald eagle disturbances to the tern colony that cause terns to flush from their nests; one tern that was satellite-tagged at the colony on Crescent Island in the Columbia Plateau region in 2015 was resighted attending a nest on the East Sand Island tern colony

5/2 – 5/8/16 ›

Monitoring continued at Caspian tern nest dissuasion areas on the east end of East Sand Island, outside the 1-acre designated Caspian tern nesting area; as many as 14 Caspian tern nests scrapes, some with eggs, were counted on the upper beach at the southeast tip of the island; all of the eggs laid in this incipient satellite colony were either depredated by gulls or washed from their nest scrapes during a high spring tide series; additional passive dissuasion materials will be deployed in this area to prevent formation of a satellite tern colony; regular hazing (nearly continuous from 0530 to 2130) is being carried out in an attempt to prevent the formation of a satellite tern colony on the upper beach just south of the main Caspian tern colony; so far no Caspian tern eggs have been observed at this incipient satellite colony site

5/2 – 5/8/15 ›

Numbers of California brown pelicans observed on East Sand Island remained low this week, apparently holding at less than 50 individuals; island-wide surveys for brown pelicans scheduled for this week were cancelled due to high winds and unsafe boating conditions around East Sand Island; a high count of 42 California brown pelicans were observed roosting on the south beach of the island near the Caspian tern colony on 8 May

5/2 – 5/8/16 ›

Predators observed on East Sand Island; bald eagle disturbance to the tern colony continued this week, causing terns to frequently flush from the colony and exposing tern eggs to gull predation; eagles were also observed stealing fish from terns returning to the colony to feed their mates; one adult tern was killed by a bald eagle on the south beach adjacent to the tern colony late in the evening, causing a major disturbance to the terns on-colony and causing most terns to leave the colony for several hours

Weekly Update for 4/25 – 5/1/2016

4/25 – 5/1/16 ›

High count for the week of an estimated 5,000 Caspian terns on East Sand Island tern colony, up from the estimated high count for the previous week (ca. 3,500); the colony as a whole has become more settled and committed to the site and nesting terns are increasingly sitting tight during regular visits to the colony by bald eagles; by the end of the week perhaps 5% of terns on-colony were attending nests with eggs

4/25 – 5/1/16 ›

Monitoring continued at Caspian tern nest dissuasion areas on the east end of East Sand Island; high counts of adult terns and tern nest scrapes on the south beach adjacent to the main tern colony were ca. 2,600 and 126, respectively; regular hazing (minimum of 5 times daily) of these birds caused them to abandon the site by the end of the week; terns are also prospecting for nest sites on the east beach, where active hazing is taking place to prevent tern nesting; to date, no Caspian tern eggs have been observed at these two incipient satellite colonies

4/25 – 5/1/15 ›

Numbers of California brown pelicans observed on East Sand Island remained low, with a high count of 4 individuals observed loafing on the southeast beach on 1 May

4/25 – 5/1/16 ›

Signs of multiple predators observed on East Sand Island; although the great horned owl was not observed this week, there were new signs of owl predation on terns discovered during the week; bald eagle disturbance to the tern colony continued this week, causing terns to frequently flush from the colony and exposing tern eggs to gull predation

4/25/16 ›

First Caspian tern egg observed on East Sand Island tern colony

Update FOR 2/26 – 4/24/2016

4/18 – 4/24/16 ›

High count for the week of an estimated 3,500 Caspian terns on East Sand Island tern colony; most terns observed on colony were loafing, while 20-30% of the birds were engaged in pre-nesting behaviors (e.g., digging nest scrapes, nest territory defense, copulation); in addition, there was a high count of 925 loafing Caspian terns on beaches near the tern colony on East Sand Island

4/18 – 4/24/16 ›

Monitoring continued at Caspian tern nest dissuasion areas at the east end of East Sand Island; up to 300 Caspian terns and 126 tern nest scrapes were observed at or just below the mean high-tide line on the beach adjacent to the main colony this week; all nest scrapes were filled in and terns using this area were actively hazed three times daily

4/18 – 4/24/16 ›

Signs of multiple predators observed on East Sand Island; great horned owl continued to cause major disturbances to nesting terns during regular nighttime visits to the colony; evidence of owl predation on adult terns was again found on or near the colony this week; bald eagle disturbance to the tern colony continued this week, causing terns to frequently flush from the colony; fresh river otter tracks were seen on the north and east beaches; a peregrine falcon, common raven, and red-tailed hawk were also observed near the tern colony this past week

4/23/16 ›

First California brown pelicans (9) observed on East Sand Island, loafing on the southeast beach)

4/18/16 ›

First evidence of Caspian terns attempting to nest outside the core 1-acre colony area on East Sand island; six nest scrapes discovered just outside of the passive nest dissuasion materials on the beach south of the colony; field crew filled in the scrapes and increased their monitoring and hazing efforts in this area

4/11 – 4/17/16 ›

High count for the week of an estimated 3,950 Caspian terns on East Sand Island tern colony; most of the terns observed on colony were loafing, while 3-5% of the birds were engaged in pre-nesting behaviors (e.g., digging nest scrapes, copulation); in addition, several hundred Caspian terns regularly were seen loafing on beaches near the main colony area on East Sand Island

4/11 – 4/17/16 ›

Signs of multiple predators observed on East Sand Island; bald eagles regularly (daily) observed on the island, causing frequent flushes of terns on the main colony area; a great horned owl is suspected of visiting the island at night, causing major disturbances to pre-nesting Caspian terns; fresh river otter tracks seen daily on the north and east beaches

4/16/16 ›

Completed colony preparations on the East Sand Island tern colony; field crew tilled and harrowed 1.0 acre of nesting habitat on the core colony area for Caspian terns, removed and repaired damaged silt fencing around the tern colony area, erected observation blinds and above-ground tunnels, set up camp for the resident colony monitors, laid out rope grids on the tern colony, spread PIT tags for detection efficiency studies, placed photo monuments for analysis of aerial photography, deployed tern decoys on core tern colony area, and installed six camera traps to monitor potential California brown pelican nesting activity on the east end of the island

4/15/16 ›

Commenced daily active hazing of Caspian terns attempting to nest on East Sand Island outside the 1.0 acre core colony area; no terns were observed in upland areas outside the core colony area on East Sand Island

4/11/16 ›

First Caspian terns (200) observed on East Sand Island tern colony

3/30 – 4/11/16 ›

Installed passive nest dissuasion materials (stakes, rope, and flagging) on 2.44 acres of potential Caspian tern nesting habitat on the east end of East Sand Island adjacent to the 1-acre core colony area

4/9/16 ›

First California brown pelicans sighted in Columbia River estuary by project staff in 2016; three seen in the water off the southeast tip of East Sand Island; no pelicans were seen on East Sand Island

3/22 – 3/26/16 ›

Installed passive nest dissuasion materials (stakes, rope, and flagging) on 2.65 acres of potential Caspian tern nesting habitat on the west end of East Sand Island

3/22/16 ›

First Caspian terns (3) observed on East Sand Island (loafing on the northwest beach)

3/21/16 ›

First Caspian tern sighted in Columbia River estuary by project staff in 2016; four terns seen flying over Tongue Point

3/9/16 ›

Seasonal field crew began work in Columbia River estuary

2/26/16 ›

Project personnel met with representatives from the U.S. Army Corps of Engineers – Portland District, Bonneville Power Administration, and the U.S. Fish and Wildlife Service for a site visit to East Sand Island in the Columbia River estuary; there was substantial erosion along the southern edge of the core Caspian tern colony; plans were developed for site clean-up, tern nesting habitat preparation (core colony area), and deployment of passive nest dissuasion materials (outside of 1-acre core colony area)

The weekly update of events at various piscivorous waterbird colonies in the Columbia River estuary

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