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

Columbia River Estuary

WEEKLY UPDATE 6/11 – 6/17/2018

6/11 – 6/17/18 ›

High count for the week of about 7,600 individual Caspian terns on the East Sand Island tern colony; this week, on average, over 60% of terns on-colony (~ 4,800 individuals) were attending nests, with an estimated 2,900 tern eggs and 2,500 tern chicks present on-colony by week’s end; the rate of tern egg losses to gull predation during frequent bald eagle flushes of the tern colony continued to decline compared to earlier in the nesting season; during these eagle disturbances, little to no tern chick mortality due to depredation by gulls was observed; in addition to the terns on the designated one-acre colony area, on average about 500 individual Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island

6/11 – 6/17/18 ›

Daily active dissuasion efforts (hazing) of Caspian terns prospecting for nest sites along the upper beach on the eastern part of East Sand Island, outside the one-acre designated colony area, were conducted 8-14 times per day this week; a total of about 130 tern nest scrapes were discovered on the upper beach and filled in on the east end of the island this week, compared to a total of about 870 tern nest scrapes found and filled in the previous week; only one intact tern egg was discovered outside the main colony area this week, compared to 11 eggs the previous week; additional passive tern nest dissuasion (stakes, rope, and flagging) was placed in the areas used by prospecting terns on the east beaches

6/11 – 6/17/18 ›

Signs of multiple predators observed on East Sand Island; bald eagles continue to cause disturbances to nesting terns on the main colony, with a total of 24 disturbances caused by bald eagles this week, compared to 27 total eagle disturbances to the colony the previous week; one depredated ring-billed gull was discovered on the east beach near the tern colony; fresh mink and otter tracks were seen near the tern colony, but no evidence was found to suggest that mammalian predators entered the designated one-acre tern colony area

WEEKLY UPDATE 6/4 – 6/10/2018

6/4 – 6/10/18 ›

High count for the week of about 7,400 individual Caspian terns on the East Sand Island tern colony; this week, on average, about 60% of terns on-colony (~ 4,200 individuals) were attending nests, with an estimated 4,300 tern eggs and 500 tern chicks present on-colony by week’s end; on 6/8 the colony experienced over an inch of rain that caused some chick mortality and egg loss due to flooding on the colony; the rate of tern egg losses to gull predation during frequent bald eagle flushes of the tern colony remained high, but continued to decline compared to earlier in the nesting season; in addition to the terns on the designated one-acre colony area, 200-1,400 individual Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island

6/4 – 6/10/18 ›

Daily active dissuasion efforts (hazing) of Caspian terns prospecting for nest sites along the upper beach on the eastern part of East Sand Island, outside the one-acre designated colony area, were conducted 14 times per day this week, with no areas of the east beaches left unhazed for more than one hour; a total of about 870 tern nest scrapes were discovered on the upper beach and filled in on the east end of the island this week, compared to a total of about 1,330 tern nest scrapes found and filled in the previous week; a total of 11 intact tern eggs were discovered outside the main colony area this week, compared to 22 eggs the previous week, all of which were either depredated or lost due to unknown causes; additional passive tern nest dissuasion (stakes, rope, and flagging) was placed in the areas used by prospecting terns on the east beaches

6/4 – 6/10/18 ›

Signs of multiple predators observed on East Sand Island; bald eagles continue to cause frequent disturbances to nesting terns on the main colony, with a total of 27 disturbances caused by bald eagles this week, compared to 38 total eagle disturbances to the colony the previous week; two depredated terns (presumably killed by a great horned owl) were discovered on the east beach near the tern colony; fresh mink scat was seen near the tern colony, but no evidence was found to suggest that mammalian predators entered the designated one-acre tern colony area

WEEKLY UPDATE 5/28 – 6/3/2018

6/2/18 ›

The first Caspian tern chicks (2) of the season were observed on the 1-acre tern colony on East Sand Island; both chicks hatched from nests located near the center of the colony

5/28 – 6/3/18 ›

High count for the week of about 7,080 individual Caspian terns on the East Sand Island tern colony; this week, on average, more than 60% of terns on-colony (~ 4,100 individuals) were attending nests, with an estimated 4,500 tern eggs present on-colony by week’s end; currently about 63%, 35%, and 2% of the nests contain 1, 2, and 3 eggs, respectively; the rate of tern egg losses to gull predation during frequent bald eagle flushes of the tern colony remained high, but began to decrease this week; in addition to the terns on the designated one-acre colony area, on average about 700 individual Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island

5/28 – 6/3/18 ›

Daily active dissuasion efforts (hazing) of Caspian terns prospecting for nest sites along the upper beach on the eastern part of East Sand Island, outside the one-acre designated colony area, were conducted 14 times per day this week, with no areas of the east beaches left unhazed for more than one hour; a total of about 1,330 tern nest scrapes were discovered on the upper beach and filled in on the east end of the island this week, compared to a total of about 1,500 tern nest scrapes found and filled in the previous week; a total of 22 intact tern eggs were discovered outside the main colony area this week, all of which were either depredated or inundated by the tide by the end of the week; additional passive tern nest dissuasion (stakes, rope, and flagging) was placed in the areas used by prospecting terns on the east beach

5/28 – 6/3/18 ›

Signs of multiple predators observed on East Sand Island; bald eagles continue to cause frequent disturbances to nesting terns on the main colony, with a total of 38 disturbances caused by bald eagles this week, compared to 55 total eagle disturbances to the colony the previous week; a depredated gull (presumably killed by an eagle) was discovered on the east beach near the tern colony; fresh mink tracks were seen on beaches surrounding the tern colony, but no evidence was found to suggest that mammalian predators entered the designated one-acre tern colony area

WEEKLY UPDATE 5/21 – 5/27/2018

5/21 – 5/27/18 ›

High count for the week of about 6,680 individual Caspian terns on the East Sand Island tern colony; this week, on average, more than 50% of terns on-colony (~ 3,700 individuals) were attending nests, with an estimated 3,500 tern eggs present on colony by week’s end; currently about 30% of the nests contain 2 eggs, with a few (3%) containing 3 eggs; the rate of tern egg losses to gull predation during frequent bald eagle flushes of the tern colony continues to be high; in addition to the terns on the designated one-acre colony area, 800-1,200 individual Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island

5/21 – 5/27/18 ›

Daily active dissuasion efforts (hazing) of Caspian terns prospecting for nest sites along the upper beach on the eastern part of East Sand Island, outside the one-acre designated colony area, were conducted 14 times per day this week, with no areas of the east beaches left unhazed for more than one hour; between 150-390 tern nest scrapes were discovered above the high tide line on the east end of the island each day this week, with over 1,500 tern nest scrapes found and filled in during the week; also, terns found in these areas were  hazed during dissuasion walk-throughs; additional passive tern nest dissuasion (stakes, rope, and flagging) was placed in the areas used by prospecting terns on the east beach; a total of 10 intact tern eggs were discovered outside the main colony area this week; all 10 eggs laid this week, including 6 intact eggs that persisting on the east beach at the end of the previous week, had been depredated by the end of the week

5/21 – 5/27/18 ›

Signs of multiple predators observed on East Sand Island; bald eagles continue to cause frequent disturbance to nesting terns, with a total of 55 disturbances caused by bald eagles this week; a depredated tern (presumably caused by an eagle) was discovered on the southeast beach near the tern colony; fresh mink and otter tracks seen on beaches surrounding the tern colony, but no evidence was found to suggest that mammalian predators entered the designated one-acre tern colony area

WEEKLY UPDATE 5/14 – 5/20/2018

5/20/18 ›

Aerial survey of the Columbia River estuary, Willapa Bay, and Grays Harbor; in the Columbia River estuary, other than at East Sand Island, 20 terns were seen loafing on Rice Island and 40 terns were observed loafing and potentially nesting at Tongue Point on the fourth pier (north to south); in Grays Harbor, about 40 terns were seen loafing on No Name Island and another 40 terns were observed on Airport Island; appreciable numbers of terns (nesting or loafing) were not observed elsewhere during this survey

5/14 – 5/20/18 ›

High count for the week of about 6,710 individual Caspian terns on the East Sand Island tern colony; the eastern half and middle of the tern colony are more settled than the western half and edges of the colony; there has been no nocturnal abandonment of the one-acre colony area by terns since 5/3; this week, on average, about 50% of terns on-colony (~ 3,500 individuals) were attending nests, with an estimated 2,200 tern eggs present on colony by week’s end; the rate of tern egg losses to gull predation during frequent bald eagle flushes of the tern colony continues to be high; in addition to the terns on the designated one-acre colony area, 1,300-2,100 individual Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island

5/14 – 5/20/18 ›

Daily active dissuasion efforts (hazing) of Caspian terns prospecting for nest sites along the upper beach on the eastern part of East Sand Island, outside the one-acre designated colony area, were conducted 14 times per day this week, with no areas of the east beaches left unhazed for more than one hour; between 70-260 tern nest scrapes were discovered above the high tide line on the east end of the island each day this week; terns found in these areas were hazed and nest scrapes were filled in during dissuasion walk-throughs; additional passive tern nest dissuasion (stakes, rope, and flagging) was placed in the areas used by prospecting terns on the east beach; a total of 16 tern eggs were discovered outside the main colony area this week, with only 6 eggs persisting on the east beach at the end of the week

5/14 – 5/20/18 ›

Signs of multiple predators observed on East Sand Island; bald eagles continue to cause frequent disturbance to nesting terns; the great horned owl was not observed this week, but two owl pellets and a depredated gull (presumably caused by an owl) were discovered on the eastern beaches near the tern colony; fresh mink and river otter tracks seen on beaches surrounding the tern colony, but no evidence was found to suggest that mammalian predators entered the designated one-acre tern colony area

WEEKLY UPDATE 5/7 – 5/13/2018

5/7 – 5/13/18 ›

High count for the week of about 6,150 individual Caspian terns on the East Sand Island tern colony, with terns now occupying 98% of the designated one-acre colony area; there has been no nocturnal abandonment of the one-acre colony area by terns since 5/3; this week, on average, 50% of terns on-colony (~ 2,500 individuals) were attending nests and the rate of egg-laying by terns has increased from previous weeks; the rate of tern egg losses to gull predation during frequent bald eagle flushes of the tern colony continues to be high; by week’s end, about 340 tern eggs were estimated to be on-colony; in addition to the terns on the designated one-acre colony area, 1,400-2,000 individual Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island; the nesting chronology of Caspian terns on East Sand Island this year remains quite late compared with average nesting chronology at this site

5/7 – 5/13/18 ›

Daily active dissuasion efforts (hazing) of Caspian terns prospecting for nest sites along the upper beach on the eastern part of East Sand Island, outside the one-acre designated colony area, were conducted 5 times per day this week;  additional forays on the beach by the dissuasion crew were conducted during periods of high nest-scraping activity by terns; between 80-370 tern nest scrapes were discovered above the high tide line on the east end of the island each day this week; terns found in these areas were hazed and nest scrapes were filled in during dissuasion walk-throughs; the first tern egg laid outside the designated one-acre colony area was discovered on 5/4; a total of 14 tern eggs were discovered outside the main colony area this week; none of these tern eggs survived 24 hours after their discovery, and apparently all were depredated by gulls

5/7 – 5/13/18 ›

Signs of multiple predators observed on East Sand Island; bald eagles continue to cause frequent disturbance; a total of 87 major disturbances to the tern colony by eagles were recorded this week; a great horned owl was once again spotted after dark, perched on the northeast observation blind next to the tern colony on 5/7; the presence of the owl near the colony did not cause widespread colony abandonment by terns as it had in the past; two adult tern carcasses were found on East Sand Island this week, one was likely killed by a great horned owl and the other died of unknown causes; fresh mink and river otter tracks seen on beaches surrounding the tern colony, but no evidence was found to suggest that mammalian predators entered the designated one-acre tern colony area

 WEEKLY UPDATE 4/30 – 5/6/2018

4/30 – 5/6/18 ›

High count for the week of about 5,350 individual Caspian terns on the East Sand Island tern colony, with terns now occupying 98% of the designated one-acre colony area; complete or partial overnight colony abandonment by terns was observed at East Sand Island on 4/30 and 5/1-5/3, respectively; while the rate of egg-laying by terns has increased since the first tern egg was seen on 4/25, the rate of tern egg losses to gull predation during frequent bald eagle flushes of the tern colony has been high, and very few eggs have persisted on-colony for more than 24 hours; by week’s end, 22 tern eggs were estimated to be on-colony; in addition to the terns on the designated one-acre colony area, 1,500-2,200 individual Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island; the nesting chronology of Caspian terns on East Sand Island this year remains quite late compared with average nesting chronology at this site

4/30 – 5/6/18 ›

Daily active dissuasion efforts (hazing) of Caspian terns prospecting for nest sites along the upper beach on the eastern part of East Sand Island, outside the one-acre designated colony area, were conducted 4 - 5 times per day this week; high count for the week of 130 tern nest scrapes was observed above the high tide line on the south beach; these terns were hazed and nest scrapes were filled in during dissuasion walk-throughs; additional passive dissuasion (i.e., stakes, rope, and flagging) was placed in the areas used by prospecting terns on the upper south and southeast beaches; no intact tern eggs have been discovered outside the one-acre designated colony area so far this season

4/30 – 5/6/18 ›

Signs of multiple predators observed on East Sand Island; bald eagles and a peregrine falcon were observed flying over island, with eagles causing frequent disturbance to nesting terns; eagles continue their aerial pursuit of Caspian terns transporting fish back to the colony in their bills for courtship feeding, and these kleptoparasitism attempts frequently lead to disturbance of terns on the main colony; bald eagles were also observed consuming a double-crested cormorant carcass on two separate occasions this past week on the north beach near the field crew camp; a great horned owl was spotted after dark, perched on an observation blind next to the tern colony on 5/2, resulting in complete colony abandonment by terns; remains of a depredated tern (likely killed by the great horned owl) were found on the north beach the following day; a total of 6 depredated bird carcasses, two of them adult terns, were found on East Sand Island this week; fresh mink tracks were seen on 5/3 along the north beach headed east, towards the tern colony

WEEKLY UPDATE 4/23 – 4/29/2018

4/25/18 ›

First Caspian tern egg (broken) observed on the 1-acre tern colony on East Sand Island; the egg was depredated by a gull; no other terns eggs were seen on colony for the rest of the week

4/23 – 4/29/18 ›

High count for the week of an estimated 4,620 Caspian terns on the East Sand Island tern colony, with terns now occupying 95% of the colony area; complete (4/23-4/24) or partial (4/25-4/29) colony abandonment by terns was observed at the East Sand Island colony every night this week; terns observed on-colony during the day were engaged mostly in pre-nesting behaviors (i.e. territory defense, digging nest scrapes, copulation, courtship feeding); in addition, 1,000-2,500 Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island

4/23 – 4/29/18 ›

Daily active dissuasion efforts (hazing) of Caspian terns prospecting for nest sites along the upper beach on the eastern part of East Sand Island, outside the one-acre designated colony area, were conducted 2 - 4 times per day this week; high count of 166 adult terns and 40 nest scrapes was observed above the high tide line on the south beach; these terns were hazed and nest scrapes were filled in during dissuasion walk-throughs; no tern eggs have been discovered so far this season outside the one-acre designated colony area

4/23 – 4/29/18 ›

Signs of multiple predators observed on East Sand Island; bald eagles and northern harriers were observed flying over island, with eagles causing frequent disturbance to nesting terns; fresh river otter and mink tracks seen daily on the north and south beaches; evidence of avian predation on an adult gull and an adult tern seen on the southeast and east beach, respectively

UPDATE 3/10 – 4/22/2018

3/12/18 ›

First visit to East Sand Island with the Corps and members of the Tern Adaptive Management Team (AMT)

3/14 – 4/15/18 ›

Preparation of one-acre of bare sand nesting habitat for Caspian terns on East Sand Island, including: (1) delineating the location of the one-acre colony area (with guidance from the Corps and the Tern AMT); (2) removing existing infrastructure (blind access tunnel and fencing) on the colony area; (3) surface preparation (herbicide treatment [by the Corps’ contractor], tilling, and disking) to remove vegetation on the colony area; (4) installation of fencing, ropes and flagging around the perimeter of the colony area to limit the designated tern nesting area to one-acre; (5) setting up grids and productivity plots used to collect data on nesting terns in the one-acre colony area; and (6) spreading PIT tags on-colony in order to estimate tag detection efficiency on the East Sand Island tern colony after the nesting season

3/17 – 4/18/18 ›

Deployment of tern passive nest dissuasion materials (stakes, rope, and flagging) on the east end of East Sand Island to prevent tern nesting outside of the designated one-acre colony area

3/28 – 4/2/18 ›

Deployment of tern passive nest dissuasion materials (stakes, rope, and flagging) on the west end of East Sand Island to prevent tern nesting

3/29/18 ›

First Caspian tern sighted in the Columbia River estuary by project staff in 2018; one individual seen flying over East Sand Island

4/2/18 ›

First Caspian terns (10 individuals) observed on East Sand Island (loafing on the southeast beach)

4/15/18 ›

First Caspian terns (710) observed on the designated one-acre tern colony area on East Sand Island

4/16 – 4/22/18 ›

High count for the week of an estimated 3,220 Caspian terns on the East Sand Island tern colony; terns observed on-colony were engaged in pre-nesting behaviors (i.e. territory defense, digging nest scrapes, copulation, courtship feeding); in addition, 1,000-1,200 Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island

4/16 – 4/22/18 ›

Signs of multiple predators observed on East Sand Island; bald eagles, northern harriers, great horned owls, peregrine falcons, and common ravens were observed occasionally flying over island; fresh river otter and mink tracks seen daily on the north, south, and southeast beaches; evidence of avian predation on an adult gull seen on the southeast beach

4/17/18 ›

First California brown pelican observed on East Sand Island (loafing on the southeast beach)

4/20/18 ›

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

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

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