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 9/19 – 9/25/2016

9/19 – 9/25/16 ›

High count for the week of 24 adult Caspian terns on the East Sand Island tern colony, much less than the high count of approximately 450 adult terns the previous week; by the end of the week, all adult and fledgling terns had left the main colony area

9/19 – 9/25/16 ›

Caspian tern nest dissuasion activities outside the 1-acre designated colony area are completed for the 2016 breeding season; all nesting attempts outside the 1-acre area this season have either failed or the young have fledged; two small satellite tern colonies had become established in areas surrounding the 1-acre designated colony area on East Sand Island this season, one on the south beach adjacent to the main tern colony and the other on the northeast beach adjacent to the ring-billed gull colony; the south beach satellite colony produced no young terns; the last tern fledglings left the northeast beach satellite tern colony the week before last

9/25/16 › 

Boat-based survey to count all California brown pelicans roosting on East Sand Island; about 2,720 brown pelicans were counted, mostly on the western half of the island

Weekly Update for 9/12 – 9/18/2016

9/12 – 9/18/16 ›

High count for the week of an estimated 450 adult Caspian terns on the East Sand Island tern colony, less than the high count of approximately 850 adult terns the previous week

9/12 – 9/18/16 ›

All Caspian tern nesting attempts outside the 1-acre designated colony area this season have either failed or the young have fledged; monitoring and nest dissuasion of Caspian terns prospecting outside the 1-acre area on the east end of East Sand Island have been discontinued; two small satellite tern colonies had become established in areas surrounding the 1-acre designated colony area on East Sand Island this season, one on the south beach adjacent to the main tern colony and the other on the northeast beach adjacent to the ring-billed gull colony; the south beach satellite colony produced no young terns; the last tern fledglings left the northeast beach satellite tern colony last week

9/16/16 ›

Only 215 adult Caspian terns and 38 chicks were present on the main Caspian tern colony, and all tern chicks were close to fledging; all tern chicks are expected to have fledged or moved off the colony by late the week of 9/19 or early the week of 9/26

9/16/16 ›

The brown pelican nest containing two eggs last week was abandoned and the eggs were missing, presumably removed by gulls; no other pelican nests with eggs or regularly attended pelican nests are present 

Weekly Update for 9/5 – 9/11/2016

9/5 – 9/11/16 ›

High count for the week of an estimated 850 adult Caspian terns on the East Sand Island tern colony, lower than the estimated high count of approximately 2,300 adult terns the previous week

9/5 – 9/11/16 ›

Monitoring and nest dissuasion of Caspian terns prospecting outside the 1-acre designated colony area continued on the east end of East Sand Island; two small satellite tern colonies had become established in areas surrounding the 1-acre designated colony area on East Sand Island, one on the south beach adjacent to the main tern colony and the other on the northeast beach adjacent to the ring-billed gull colony; the south beach satellite colony has been abandoned, with no young terns produced at the site; the northeast beach satellite tern colony remains active, with up to 24 adult terns and 4 black-capped tern chicks counted; total numbers of terns observed loafing on the beaches surrounding the 1-acre designated nesting area were about 50-200 individuals this week, less than the previous week (100-500 individuals)

9/5 – 9/11/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony continued this week; more evidence of peregrine falcon depredation of Caspian tern fledglings was observed on the beach this week 

9/10/16 › 

During a bald eagle disturbance that cleared all brown pelicans from the south beach, eight brown pelican nests were counted and one nest contained 2 pelican eggs; all other pelican nests were empty 

9/8/16 › 

Boat-based survey of all roosting California brown pelicans conducted at East Sand Island; about 3,850 adult brown pelicans were counted throughout the island 

Weekly Update for 8/29 – 9/4/2016

8/29 – 9/4/16 ›

High count for the week of an estimated 2,300 individual adult Caspian terns on the East Sand Island tern colony, less than to the estimated high count of approximately 4,200 adult terns the previous week

8/29 – 9/4/16 ›

Monitoring and nest dissuasion of Caspian terns prospecting outside the 1-acre designated colony area continued on the east end of East Sand Island; two small satellite tern colonies had become established in areas surrounding the 1-acre designated colony area on East Sand Island, one on the south beach adjacent to the main tern colony and the other on the northeast beach adjacent to the ring-billed gull colony; the south beach satellite colony has been abandoned, with no adult terns in incubation posture counted at the site; the northeast beach satellite tern colony remains active, with 22 adult terns and 5 tern chicks counted; total numbers of terns observed loafing on the beaches surrounding the 1-acre designated nesting area were about 100-500 individuals this week, less than the previous week (400-800 individuals)

8/29 – 9/4/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony continues, but at a much lower frequency than earlier in the nesting season; more evidence of peregrine falcon depredation of Caspian tern fledglings was observed on the beach this week

Weekly Update for 8/22 – 8/28/2016

8/22 – 8/28/16 ›

High count for the week of an estimated 4,200 individual adult Caspian terns on the East Sand Island tern colony, similar to the estimated high count of approximately 4,700 adult terns the previous week

8/22 – 8/28/16 ›

Monitoring and nest dissuasion of Caspian terns prospecting outside the 1-acre designated colony area continued on the east end of East Sand Island; two small satellite tern colonies had become established in areas surrounding the 1-acre designated colony area on East Sand Island, one on the south beach adjacent to the main tern colony and the other on the northeast beach adjacent to the ring-billed gull colony; the south beach satellite colony has been abandoned, with no adult terns in incubation posture counted at the site; the northeast beach satellite tern colony remains active, with 70 adult terns, 17 attended tern nests, and 17 tern chicks counted; total numbers of terns observed loafing on the beaches surrounding the 1-acre designated nesting area were about 400-800 individuals this week, somewhat less than the previous week (400-1,350 individuals)

8/22 – 8/28/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony continues, but at a much lower frequency than earlier in the nesting season; more evidence of peregrine falcon depredation of Caspian tern fledglings was observed on the beach this week; fresh mink and river otter tracks were observed on the north beach, near the field camp 

8/25/16 › 

291 Caspian tern chicks near fledging age were captured on the main tern colony and banded with field-readable plastic leg bands and engraved metal federal leg bands on East Sand Island in the Columbia River estuary; 19 smaller Caspian tern chicks were banded metal federal leg bands only 

8/25/16 › 

Two attended California brown pelican nests were discovered at the base of the bluff overlooking the south beach on East Sand Island, just to the west of the main Caspian tern colony; one nest was confirmed to contain three eggs 

Weekly Update for 8/15 – 8/21/2016

8/15 – 8/21/16 ›

High count for the week of an estimated 4,700 individual adult Caspian terns on the East Sand Island tern colony, similar to the estimated high count of approximately 4,350 terns the previous week; a total of ca. 545 attended tern nests, ca. 90 recently hatched downy tern chicks, ca. 20 mid-sized tern chicks, ca. 270 tern chicks in the black-mask stage of plumage development, and ca. 720 nearly fledged chicks in the black-capped stage of plumage development were also counted on-colony this week; these counts of tern chicks in different stages of plumage development demonstrate that the second wave of tern egg hatching is waning on the main tern colony

8/15 – 8/21/16 ›

Monitoring and nest dissuasion of Caspian terns prospecting outside the 1-acre designated colony area continued on the east end of East Sand Island; two small satellite tern colonies had become established in areas surrounding the 1-acre designated colony area on East Sand Island, one on the south beach adjacent to the main tern colony and the other on the northeast beach adjacent to the ring-billed gull colony; the south beach satellite colony has been abandoned, with no adult terns in incubating posture counted at the site; the northeast beach satellite tern colony remains active, with 28 attended tern nests and 13 tern chicks counted; total numbers of terns observed loafing on the beaches surrounding the 1-acre designated nesting area were about 400-1,350 individuals this week, similar to the previous week (350-900 individuals); daily hazing of prospecting terns outside the 1-acre designated colony area on East Sand Island continues

8/15 – 8/21/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony continues, but at a much lower frequency; evidence of peregrine falcon depredation on adult terns, gulls, and cormorants was observed on the beach this week; fresh mink and river otter tracks were observed on the north beach, near the field camp 

8/15/16 › 

Boat-based survey of roosting California brown pelicans conducted at East Sand Island; about 5,075 brown pelicans counted throughout the island, the majority were counted on the south shoreline near the Caspian tern colony at the eastern end of the island

Weekly Update for 8/8 – 8/14/2016

8/8 – 8/14/16 ›

High count for the week of an estimated 4,350 individual adult Caspian terns on the East Sand Island tern colony, lower than the estimated high count of approximately 5,500 terns the previous week; a total of about 630 attended tern nests, about 290 recently hatched downy tern chicks, about 630 mid-sized tern chicks, about 290 tern chicks in the black-mask stage of plumage development, and about 125 nearly fledged chicks in the black-capped stage of plumage development were also counted on-colony this week; these counts of tern chicks in different stages of plumage development demonstrate that the second wave of tern egg hatching is waning on the main tern colony

8/8 – 8/14/16 ›

Monitoring and nest dissuasion of Caspian terns prospecting outside the 1-acre designated colony area continued on the east end of East Sand Island; two small satellite tern colonies had become established in areas surrounding the 1-acre designated colony area on East Sand Island, one on the south beach adjacent to the main tern colony and the other on the northeast beach adjacent to the ring-billed gull colony; the south beach satellite colony has been abandoned, with no adult terns in incubating posture counted at the site; the northeast beach satellite tern colony remains active, with 16 attended tern nests and 9 tern chicks counted; total numbers of terns observed loafing on the beaches surrounding the 1-acre designated nesting area were about 350-900 individuals this week, similar to the previous week (300-1,000 individuals); daily hazing of prospecting terns outside the 1-acre designated colony area on East Sand Island continues

8/8 – 8/14/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony continues, but at a much lower frequency; evidence of peregrine falcon depredation on adult terns and gulls was observed on the beach this week; fresh mink tracks were observed on the north beach, near the field camp

Weekly Update for 8/1 – 8/7/2016

8/1 – 8/7/16 ›

High count for the week of an estimated 5,500 individual adult Caspian terns on the East Sand Island tern colony, lower than the estimated high count of approximately 6,450 terns the previous week; a total of ca. 1,220 attended tern nests, ca. 160 recently hatched downy tern chicks, ca. 900 mid-sized tern chicks, ca. 70 tern chicks in the black-mask stage of plumage development, and ca. 410 nearly fledged chicks in the black-capped stage of plumage development were also counted on-colony this week; these counts of tern chicks in different stages of plumage development demonstrate that the second wave of tern egg hatching is waning on the main tern colony, and the younger cohort of tern chicks is about half grown

8/1 – 8/7/16 ›

Monitoring and nest dissuasion of Caspian terns prospecting outside the 1-acre designated colony area continued on the east end of East Sand Island; two small satellite tern colonies had become established in areas surrounding the 1-acre designated colony area on East Sand Island, one on the south beach adjacent to the main tern colony and the other on the northeast beach adjacent to the ring-billed gull colony; this week, the south beach satellite colony continued to decline, with only four adult terns in incubating posture counted at the site; the northeast beach satellite tern colony remains more active, with about 75 adult Caspian terns present, 47 attended tern nests counted, and 4 tern chicks seen; total numbers of terns observed loafing on the beaches surrounding the 1-acre designated nesting area were about 300-1,000 individuals this week, somewhat lower than the previous week (700-1,200 individuals); daily hazing of prospecting terns outside the 1-acre designated colony area on East Sand Island continues, although the presence of active tern nests with eggs constrains some nest dissuasion activities

8/1 – 8/7/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony continues, but at a lower frequency; evidence of peregrine falcon depredation on adult terns and gulls was observed on the beach this week; fresh river otter and mink tracks were observed repeatedly on the north beach, near the field camp 

8/4/16 › 

Two boat-based surveys of roosting California brown pelicans were conducted at East Sand Island, one during mid-day and the other at dusk to test whether more pelican were using the island as a day roost than as a night roost; about 5,280 brown pelicans were counted throughout the island at mid-day and about 3,890 brown pelicans were counted throughout the island at dusk, confirming that more pelicans were roosting on the island during the day; the pelican counts on the east end of the island remained relatively consistent between the mid-day and evening counts (about 3,000 individuals), while the pelican counts on the west end of the island were higher during the day (about 2,000 individuals) compared to during the evening (about 1,000 individuals); this is the first time this season that appreciable numbers of California brown pelicans were observed roosting on the west end of East Sand Island

Weekly Update for 7/25 – 7/31/2016

7/25 – 7/31/16 ›

High count for the week of an estimated 6,450 individual adult Caspian terns on the East Sand Island tern colony, similar to the estimated high count of approximately 6,200 terns the previous week; a total of ca. 1,130 attended tern nests, ca. 860 recently hatched downy tern chicks, 42 mid-sized tern chicks, 41 black-masked tern chicks, and ca. 620 nearly fledged black-capped chicks were also counted on colony this past week; these counts of tern chicks in different stages of plumage development demonstrate that a second wave of tern egg hatching on the main tern colony is well underway

7/25 – 7/31/16 ›

Monitoring and nest dissuasion of Caspian terns prospecting outside the 1-acre designated colony area continued on the east end of East Sand Island; two small satellite tern colonies have become established in areas surrounding the 1-acre designated colony area on East Sand Island, one on the south beach adjacent to the main tern colony and the other on the northeast beach adjacent to the ring-billed gull colony; in total, ca. 575 terns were counted on these two satellite colonies this week, with 70 of those attending apparently active nests, down from 102 active nest the previous week; 18 Caspian tern chicks were counted on the northeast beach satellite colony this week, while no Caspian tern chicks were observed at the south beach satellite colony; total numbers of terns observed loafing on the beaches surrounding the 1-acre designated nesting area were 700-1,200 individuals this week, similar to the previous week; daily hazing of prospecting terns outside the 1-acre designated colony area on East Sand Island continues, although the presence of active tern nests with eggs continues to constrain some nest dissuasion activities

7/25 – 7/31/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony continues; fresh American mink and river otter tracks were observed on the north beach, near the field camp 

7/28/16 › 

Sixth boat-based survey of roosting California brown pelicans conducted at East Sand Island this season; ca. 3,050 brown pelicans counted throughout the island, all on the south shoreline near the Caspian tern colony at the eastern end of the island

Weekly Update for 7/18 – 7/24/2016

7/18 – 7/24/16 ›

High count for the week of an estimated 6,200 individual Caspian terns on the East Sand Island tern colony, slightly lower than the estimated high count of approximately 6,720 terns the previous week; a total of ca. 1,150 tern chicks were counted on colony this week, nearly 40% were recently hatched (downy chicks) and represent the second wave of nests hatching that were initiated after nest losses that occurred during bald eagle disturbances earlier in the breeding season  

7/18 – 7/24/16 ›

Monitoring and nest dissuasion of Caspian terns prospecting outside the 1-acre designated colony area continued on the east end of East Sand Island; two small satellite tern colonies have become established in areas surrounding the 1-acre designated colony area on East Sand Island, one on the south beach adjacent to the main tern colony (which is smaller this week compared to the previous week) and the other on the northeast beach adjacent to the ring-billed gull colony (which is similar in size this week compared to the previous week);  in total, ca. 450 terns were counted on these satellite colonies, with ca. 100 of those apparently attending nests; total numbers of terns observed loafing on the beaches surrounding the 1-acre designated nesting area were 700-1,200 individuals this week, similar to the previous week; daily hazing of prospecting terns outside the 1-acre designated colony area on East Sand Island continues, although the presence of active tern nests with eggs constrains some nest dissuasion activities

7/18 – 7/24/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony continues; fresh American mink and river otter tracks were observed on the north beach, near the field camp

Weekly Update for 7/11 – 7/17/2016

7/11 – 7/17/16 ›

High count for the week of an estimated 6,720 individual Caspian terns on the East Sand Island tern colony, similar to the estimated high count of approximately 6,340 terns the previous week

7/11 – 7/17/16 ›

Monitoring and nest dissuasion of Caspian terns prospecting outside the 1-acre designated colony area continued on the east end of East Sand Island; two small satellite tern colonies have become established in areas surrounding the 1-acre designated colony area on East Sand Island, one on the south beach adjacent to the main tern colony (which is smaller this week compared to the previous week) and the other on the northeast beach adjacent to the ring-billed gull colony (which is similar in size this week compared to the previous week); total numbers of terns observed loafing on the beaches surrounding the 1-acre designated nesting area were 600-1,200 individuals this week, the same as the previous week; daily hazing of prospecting terns outside the 1-acre designated colony area on East Sand Island continues, although the presence of active tern nests with eggs has constrained some nest dissuasion activities

7/11 – 7/17/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony continues; dead fledgling tern observed with wounds consistent with predation by an American mink; trail cam captured photographs of an American mink on the east end of the island this past week 

7/16/16 › 

Fifth boat-based survey of roosting California brown pelicans conducted at East Sand Island this season; ca. 3,800 brown pelicans counted throughout the island, mainly below the wrack line on the eastern end of the island

Weekly Update for 7/4 – 7/10/2016

7/4 – 7/10/16 ›

High count for the week of an estimated 6,340 individual Caspian terns on the East Sand Island tern colony, similar to the estimated high count of approximately 6,660 terns the previous week; the majority of tern chicks on-colony are in the black-mask or black-cap stage of plumage development, and are therefore 2 weeks or more post-hatching

7/4 – 7/10/16 ›

Monitoring and nest dissuasion of Caspian terns prospecting outside the 1-acre designated colony area continued on the east end of East Sand Island; two small satellite tern colonies have become established in areas surrounding the 1-acre designated colony area on East Sand Island, one on the south beach adjacent to the main tern colony and the other on the northeast beach adjacent to the ring-billed gull colony; high tides early in the week reduced the size of the south beach satellite colony to about 100 nests with eggs, about half of these with an incubating adult; a night-time disturbance on 10 July, perhaps caused by a great horned owl, reduced the size of the northeast beach satellite colony by roughly half (currently 100-125 attended nests); total numbers of terns observed loafing on the beaches surrounding the 1-acre designated nesting area were 600-1,200 individuals this week, similar to the previous week (700-1,200 individuals); daily hazing of prospecting terns outside the 1-acre designated colony area on East Sand Island continues, although the presence of active tern nests with eggs has constrained some nest dissuasion activities

7/4 – 7/10/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony has declined in recent weeks; peregrine falcons are causing disturbance to loafing birds on the east beach; fresh American mink tracks were observed on the north beach, near the field camp (a camera trap at a bait station was set up on the north beach in an attempt to photograph the mink) 

7/6/16 › 

First Caspian tern fledgling observed on the East Sand Island colony 

Weekly Update for 6/27 – 7/3/2016

6/27 – 7/3/16 ›

High count for the week of an estimated 6,660 individual Caspian terns on the East Sand Island tern colony, similar to the estimated high count of approximately 6,850 terns the previous week; the number of Caspian tern nests with downy chicks increased this week, associated with a second wave of hatching on the colony; the majority of tern chicks on-colony are in the black-cap or downy stage of plumage development, with only a few chicks in the black-mask phase (i.e. mid-sized chicks)

6/27 – 7/3/16 ›

Monitoring and nest dissuasion of Caspian terns prospecting outside the 1-acre designated colony area continued on the east end of East Sand Island; two small satellite tern colonies have become established in areas surrounding the 1-acre designated colony area on East Sand Island, one on the south beach adjacent to the main tern colony and the other on the northeast beach adjacent to the ring-billed gull colony; a total of 137 tern eggs are still present and are being attended on these two satellite colonies; total numbers of terns observed loafing on the beaches surrounding the 1-acre nesting area were 700-1,200 individuals this week, similar to the previous week (600-1,200 individuals); daily hazing of prospecting terns outside the 1-acre designated colony area on East Sand Island continues, although the presence of active tern nests with eggs has constrained some nest dissuasion activities

6/27 – 7/3/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony has declined in recent weeks; signs of avian predation on adult and juvenile Caspian terns were discovered; fresh American mink and river otter tracks were observed on the north beach, near the field camp 

7/1/16 › 

Fourth boat-based survey of roosting California brown pelicans conducted at East Sand Island this season; ca. 2,650 brown pelicans counted throughout the island, mainly below the wrack line on the eastern end of the island 

Weekly Update for 6/20 – 6/26/2016

6/20 – 6/26/16 ›

High count for the week of an estimated 6,850 individual Caspian terns on the East Sand Island tern colony, slightly lower than the estimated high count of ca. 7,290 terns the previous week; tern eggs and tern chicks (downy, black-masked, and black-capped) are currently on the colony; new tern eggs have been laid across much of the area around the periphery of the tern colony where nest failure due to gull predation occurred in previous weeks

6/20 – 6/26/16 ›

Monitoring and nest dissuasion of Caspian terns prospecting outside the 1-acre designated colony area continued on the east end of East Sand Island; a total of 47 tern eggs were laid on the south beach this week, mostly outside the areas covered by passive dissuasion materials on the east end of East Sand Island; daily hazing of prospecting terns on the south beach has been reduced due to the presence of active tern nests with eggs that have restricted dissuasion activities; this satellite tern colony will likely fail during high tide events in the coming weeks; total numbers of terns observed loafing on the beaches surrounding the 1-acre nesting area were 600-1,200 individuals this week, similar to the previous week (500-1,400 individuals)

6/20 – 6/26/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony decreased this week; signs of predation on adult and juvenile Caspian terns were discovered, apparently by bald eagles and mink; fresh American mink tracks were observed on the north beach, near the field camp

Weekly Update for 6/13 – 6/19/2016

6/13 – 6/19/16 ›

High count for the week of an estimated 7,290 individual Caspian terns on the East Sand Island tern colony, a slight decrease from the estimated high count of ca. 7,980 terns the previous week; tern eggs, downy tern chicks, and black-masked tern chicks are currently on the colony; ca. 10% of the tern nests located along the perimeter of the colony have been abandoned, presumably due to an increase in nest predation by gulls during eagle disturbances; a nesting attempt by a Caspian tern that was satellite-tagged at the colony on Crescent Island in the Columbia Plateau region in 2015 has failed and that bird is now loafing on-colony

6/13 – 6/19/16 ›

Monitoring and nest dissuasion of prospecting Caspian terns outside the 1-acre designated nesting area continued on the east end of East Sand Island; 2 tern eggs were discovered on the south beach, outside of areas covered by passive dissuasion materials on the east end of East Sand Island; both Caspian tern eggs were apparently depredated by gulls or washed away during high tide events within 24 hours of discovery; intensity of nest-scraping by terns continues to decline, with no new nest scrapes observed on the north, east, and southeast beaches this week; daily hazing is being conducted in an attempt to prevent the formation of satellite tern colonies on the upper beaches at the eastern end of the island near the main Caspian tern colony; total numbers of terns observed loafing on the beaches surrounding the 1-acre nesting area were 500-1,400 individuals this week, slightly higher than the previous week (500-1,000 individuals)

6/13 – 6/19/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony continued and intensified this week, causing terns to flush from the colony and exposing tern eggs to gull predation; fresh river otter and American mink tracks were observed on the north beach, west of the field camp; evidence of predation by a peregrine falcon also observed

6/19/16 ›

Aerial photography census to estimate numbers of Caspian terns nesting on East Sand Island was conducted this week; counts from aerial photography later in the season will allow us to more accurately estimate the number of breeding pairs of Caspian terns and the area of nesting habitat occupied by terns at the prepared colony site

6/18/16 ›

Third boat-based survey of roosting California brown pelicans conducted at East Sand Island this season; ca. 700 brown pelicans counted throughout the island, mainly below the wrack line on the south and southeast beaches

Weekly Update for 6/6 – 6/12/2016

6/6 – 6/12/16 ›

High count for the week of an estimated 7,980 individual Caspian terns on the East Sand Island tern colony, a slight increase from the estimated high of ca. 7,400 terns the previous week; 50-60% of tern nests now contain at least one chick; tern eggs continue to be laid in new nest scrapes and in nests that were depredated by gulls; bald eagle disturbances to the tern colony remain common; one Caspian tern that was satellite-tagged at the colony on Crescent Island in the Columbia Plateau region in 2015 continues to attend a nest with one egg on the East Sand Island tern colony; a satellite-tagged Caspian tern that was originally banded as an adult on Goose Island in 2012 and satellite–tagged on Crescent Island in 2015 was observed loafing on the East Sand Island tern colony

6/6 – 6/12/16 ›

Monitoring and Caspian tern nest dissuasion continued on the east end of East Sand Island, outside the 1-acre designated Caspian tern nesting area; 10 tern eggs were discovered on the south and northeast beaches, just outside of areas covered by passive dissuasion materials on the east end of East Sand Island; all 10 Caspian tern eggs were apparently depredated by gulls or washed away during high tide events within 24 hours of discovery; intensity of nest-scraping by terns declined this week, with no new nest scrapes observed on the north, east, and southeast beaches this week; daily hazing is being conducted in an attempt to prevent the formation of satellite tern colonies on the upper beaches at the eastern end of the island near the main Caspian tern colony; total numbers of terns observed loafing on the beaches surrounding the 1-acre nesting area were 500-1,000 individuals this week, similar to the previous week (600-1,000 individuals)

6/6 – 6/12/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony continued and somewhat intensified this week, causing terns to flush from the colony and exposing tern eggs to gull predation; colony-wide flushes occurred at dusk on several occasions this week, believed to be caused by a great horned owl; fresh river otter and American mink tracks were observed on the north beach, west of the field camp

6/6 & 6/12/16 ›

Two aerial photography censuses to estimate numbers of Caspian terns nesting on East Sand Island were conducted this week; counts from aerial photography later in the season will allow us to more accurately estimate the number of breeding pairs of Caspian terns and the area of nesting habitat occupied by terns at the prepared colony site

Weekly Update for 5/30 – 6/5/2016

5/30 – 6/5/16 ›

High count for the week of an estimated 7,400 individual Caspian terns on the East Sand Island tern colony, similar to the estimated high of ca. 7,450 terns the previous week; ca. 10% of tern nests now contain at least one chick; the first Caspian tern chicks were observed on colony on 26 May; bald eagle disturbances to the tern colony remains common, however less frequent than has been observed in previous weeks; one Caspian tern that was satellite-tagged at the colony on Crescent Island in the Columbia Plateau region in 2015 continues to attend a nest with one egg on the East Sand Island tern colony

5/30 – 6/5/16 ›

Monitoring and Caspian tern nest dissuasion continued on the east end of East Sand Island, outside the 1-acre designated Caspian tern nesting area; 6 tern eggs were discovered outside of areas covered by passive dissuasion materials on the south and northeast beaches, and all were apparently depredated by gulls or washed away during high tide events within 24 hours of discovery; daily hazing (nearly continuous from 0530 to 2130) is being conducted in an attempt to prevent the formation of satellite tern colonies on the upper beaches at the eastern end of the island near the main Caspian tern colony; total numbers of terns observed loafing on the beaches surrounding the 1-acre nesting area were 600-1,000 individuals this week, similar to the previous week (400-900 individuals)

5/30 – 6/5/16 ›

Predators observed on East Sand Island this week; bald eagle disturbance to the Caspian tern colony continued, causing terns to flush from the colony and exposing tern eggs to gull predation; a peregrine falcon was suspected of killing adult terns and other avian species on the east end of the island; colony-wide flushes occurred after dusk on several occasions this past week, believed to be caused by a great horned owl; fresh river otter tracks were observed on the north beach

6/4/16 ›

Second boat-based survey of roosting California brown pelicans conducted at East Sand Island this season; ca. 1,120 brown pelicans counted throughout the island, nearly all on at the east end of the island, near the Caspian tern colony; as many as 1,700 brown pelicans were counted on the beach near the tern colony at around mid-day

5/30/16 ›

Aerial photo census to estimate numbers of Caspian terns nesting on East Sand Island; counts from aerial photography later in the season will allow us to more accurately estimate the number of breeding pairs of Caspian terns and the area of nesting habitat occupied by terns at this prepared colony site

Weekly Update for 5/23 – 5/29/2016

5/23 – 5/29/16 ›

High count for the week of an estimated 7,450 individual Caspian terns on the East Sand Island tern colony, higher than the estimated high of an estimated 6,550 terns the previous week; the first Caspian tern chicks were observed on colony on 26 May; egg depredation rates by gulls around the periphery of the tern colony remains high, usually associated with bald eagle disturbances 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 confirmed attending a nest with one egg on the East Sand Island tern colony

5/23 – 5/29/16 ›

Monitoring and Caspian tern nest dissuasion continued on the east end of East Sand Island, outside the 1-acre designated Caspian tern nesting area; 15 tern eggs were discovered outside of areas covered by passive dissuasion materials on the south, southeast, and northeast beaches, and all were apparently depredated by gulls within 24 hours of discovery; daily hazing (nearly continuous from 0530 to 2130) is being conducted in an attempt to prevent the formation of satellite tern colonies on the upper beaches at the eastern end of the island near the main Caspian tern colony; total numbers of terns observed loafing on the beaches surrounding the 1-acre nesting area were 400-900 individuals this week, similar to the previous week (400-1,000 individuals)

5/23 – 5/29/16 ›

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; colony-wide flush occurred after dusk on 28 May, believed to be caused by a great horned owl; fresh river otter tracks were observed on the north beach

5/26/16 ›

First Caspian tern chick observed so far this season on the East Sand Island colony

5/23/16 ›

Aerial photo census to estimate numbers of Caspian terns nesting on East Sand Island; counts of aerial photography later in the season will allow us to more accurately estimate the number of breeding pairs of Caspian terns and the area of nesting habitat occupied by terns at this prepared colony site

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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