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

Columbia River Estuary

WEEKLY UPDATE 8/6 – 8/12/2018

8/6 – 8/12/18 ›

High count for the week of about 3,750 individual Caspian terns, approximately 2,200 attended tern nests, and roughly 430 tern chicks on the East Sand Island tern colony, down from estimates the previous week (4,340 individuals, 2,900 nests, and 900 chicks); the majority of tern chicks on-colony were in the black-cap (nearly fledged) stage of plumage development, although there were also tern eggs and young chicks still on the colony; the colony was more settled this week and previous two weeks, with a total of 2 observed disturbances to the tern colony during each week; in addition to terns on the designated one-acre colony area, an average of about 870 individual Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island

8/6 – 8/12/18 ›

Daily active dissuasion (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, was conducted 1-2 times per day on four days this week; a total of about 142 tern nest scrapes were discovered on the upper beach and filled-in this week, compared to about 207 tern nest scrapes the previous week; no tern eggs were discovered outside the main colony area this week or the previous week; no tern eggs laid outside the one-acre designated colony area have persisted this season, and no Caspian tern satellite colonies have formed on East Sand Island during the 2018 breeding season

8/6 – 8/12/18 ›

Signs of multiple predators observed on East Sand Island; bald eagles continue to cause minor disturbances to nesting terns on the main colony, with only two observed disturbances caused by bald eagles in each of the previous three weeks; during the week, over 50 carcasses of piscivorous waterbirds (i.e., terns, cormorants, and gulls), mostly chicks, were found on the east beaches of East Sand Island; the bird carcasses found on the eastern part of East Sand Island this week were believed to have been depredated by avian predators (e.g., bald eagles, peregrine falcons) or, in the case of most of the tern chick carcasses, the result of starvation

WEEKLY UPDATE 7/30 – 8/5/2018

7/30 – 8/5/18 ›

High count for the week of about 4,340 individual Caspian terns, approximately 2,900 attended tern nests, and roughly 900 tern chicks on the East Sand Island tern colony, down from estimates the previous week (4,780 individuals, 3,100 nests, and 1,200 chicks); the majority of tern chicks on-colony were in the black-cap (nearly fledged) stage of plumage development, although there were also tern eggs and young chicks still on the colony; the colony was more settled the past couple of weeks, with a total of 2 observed disturbances in each of the previous two weeks; in addition to terns on the designated one-acre colony area, an average of about 1,000 individual Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island

7/30 – 8/5/18 ›

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 1-2 times per day this week; a total of about 207 tern nest scrapes were discovered on the upper beach and filled-in this week, compared to about 139 tern nest scrapes the previous week; no tern eggs were discovered outside the main colony area in the last two weeks; no tern eggs laid outside the one-acre designated colony area have persisted, and no Caspian tern satellite colonies have formed on East Sand Island so far this season

7/30 – 8/5/18 ›

Signs of multiple predators observed on East Sand Island; bald eagles continue to cause minor disturbances to nesting terns on the main colony, with only two observed disturbances caused by bald eagles in each of the previous two weeks; during the week, 51 Caspian tern chick carcasses, 10 ring-billed gull chick carcasses, and two western/glaucous-winged gull chick carcasses were found on the east beaches of East Sand Island; most or all of the bird carcasses found on the eastern part of East Sand Island this week were believed to have been depredated by avian predators (e.g., bald eagles and peregrine falcons)

WEEKLY UPDATE 7/23 – 7/29/2018

7/23 – 7/29/18 ›

High count for the week of about 4,780 individual Caspian terns, approximately 3,100 attended tern nests, and roughly 1,200 tern chicks on the East Sand Island tern colony, down from estimates the previous week (5,810 individuals, 3,700 nests, and 2,400 chicks); the majority of tern chicks on-colony were in the black-cap (nearly fledged) stage of plumage development, although there were also tern eggs and young chicks still on the colony; the colony was more settled this week compared to previous weeks, with a total of 2 observed disturbances during the week compared to 3 disturbances the previous week; in addition to terns on the designated one-acre colony area, an average of about 500 individual Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island

7/23 – 7/29/18 ›

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 2-5 times per day this week; a total of about 139 tern nest scrapes were discovered on the upper beach and filled-in this week, compared to about 149 tern nest scrapes the previous week; no tern eggs were discovered outside the main colony area this week, compared to three eggs the previous week; to date, a few tern eggs laid outside the one-acre designated colony area may have persisted and been incubated by adults, but are unlikely to hatch because the nests are located in marginal habitat (i.e., at the high tide line), plus the low probability of nesting success for nests initiated so late in the season

7/23 – 7/29/18 ›

Signs of multiple predators observed on East Sand Island; bald eagles continue to cause minor disturbances to nesting terns on the main colony, with only two observed disturbances caused by bald eagles this week, compared to one observed eagle disturbance the previous week; during the week, two adult Caspian tern carcasses, 38 Caspian tern chick carcasses, one adult ring-billed gull carcass, 22 ring-billed gull chick carcasses, one adult California brown pelican carcass, and one American crow carcass were found on the east beaches of East Sand Island; most or all of the bird carcasses found on the eastern part of East Sand Island this week were believed to have been depredated by avian predators (e.g., bald eagles and peregrine falcons)

WEEKLY UPDATE 7/16 – 7/22/2018

7/16 – 7/22/18 ›

High count for the week of about 5,810 individual Caspian terns, approximately 3,700 attended tern nests, and roughly 2,400 tern chicks on the East Sand Island tern colony, down slightly from the previous week (6,600 individuals, 4,000 nests, and 2,800 chicks); the majority of tern chicks on-colony were in the black-cap (nearly fledged) stage of plumage development, although there are also eggs and young chicks still on the colony; the colony was settled this week compared to previous weeks, with 3 total disturbances observed this week compared to 7 total disturbances last week; in addition to terns on the designated one-acre colony area, on average of about 610 individual Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island

7/16 – 7/22/18 ›

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 5-6 times per day this week; a total of about 149 tern nest scrapes were discovered on the upper beach and filled-in this week, compared to about 34 tern nest scrapes the previous week; three tern eggs were discovered outside the main colony area this week, compared to no eggs the previous week; to date, only one tern egg laid outside the one-acre designated colony area has persisted, and no Caspian tern satellite colonies have formed so far this season

7/16 – 7/22/18 ›

Signs of multiple predators observed on East Sand Island; bald eagles continue to cause minor disturbances to nesting terns on the main colony; peregrine falcons have been relatively absent from East Sand Island this season, but one was observed near the tern colony this week; during the week, two adult gull carcasses were found on the east beaches of East Sand Island, as well as the carcasses of 34 ring-billed gull chicks and 14 Caspian tern chicks; fresh signs of mink and river otter 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 7/9 – 7/15/2018

7/10/18 ›

The first Caspian tern fledgling of the season was observed near the 1-acre tern colony on East Sand Island

7/9 – 7/15/18 ›

High count for the week of about 6,600 individual Caspian terns, approximately 4,000 attended tern nests, and roughly 2,800 tern chicks on the East Sand Island tern colony, down slightly from the previous week (6,910 individuals, 4,500 nests, and 3,300 chicks); the majority of tern chicks on-colony were in the black-cap (nearly fledged) stage of plumage development; the colony was fairly settled this week compared to previous weeks, with only 7 total disturbances observed this week compared to 25 total disturbances last week; in addition to the terns on the designated one-acre colony area, on average of about 590 individual Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island

7/9 – 7/15/18 ›

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 5-8 times per day this week; a total of about 34 tern nest scrapes were discovered on the upper beach and filled-in this week, compared to about 120 tern nest scrapes the previous week; no tern egg were discovered outside the main colony area this week, compared to one egg the previous week; to date, no tern eggs laid outside the one-acre designated colony area have persisted, and no Caspian tern satellite colonies have formed so far this season

7/9 – 7/15/18 ›

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 5 disturbances (mostly minor) caused by bald eagles this week, compared to 19 eagle disturbances the previous week; on three separate occasions this week, bald eagles were observed depredating adult and juvenile ring-billed gulls on the northeast beach; during the week, one carcass of an adult cormorant, one carcass of an adult common loon, and two adult gull carcasses were found on the east beaches of East Sand Island, as well as the carcasses of 20 ring-billed gull chicks and 11 Caspian tern chicks; fresh mink and river 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 7/2 – 7/8/2018

7/2 – 7/8/18 ›

High count for the week of about 6,910 individual Caspian terns with an estimated 4,500 attended tern nests on the East Sand Island tern colony, similar to estimates from the previous week (6,960 individuals and 4,900 nests); the estimated number of tern chicks (3,300) on the East Sand Island tern colony this week was slightly lower than the estimate the previous week (3,800 chicks); the majority of tern chicks on-colony were in the black-mask to black-cap stage of plumage development; there was a higher level of disturbance to the tern colony this week compared to the previous week, with 19 out of 25 total disturbances observed this week being caused by bald eagle overflights; in addition to the terns on the designated one-acre colony area, on average about 480 individual Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island

7/2 – 7/8/18 ›

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 7-8 times per day this week; a total of about 120 tern nest scrapes were discovered on the upper beach and filled-in this week, compared to about 290 tern nest scrapes the previous week; one intact tern egg was discovered outside the main colony area this week, compared to 7 eggs the previous week; to date, no tern eggs laid outside the one-acre designated colony area have persisted, and no Caspian tern satellite colonies have formed

7/2 – 7/8/18 ›

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 19 disturbances (mostly minor) caused by bald eagles this week, compared to 11 eagle disturbances the previous week; during the week, one carcass of an adult cormorant and two carcasses of adult ring-billed gulls were found on the east beaches of East Sand Island, as well as the carcasses of 13 ring-billed gull chicks and one Caspian tern chick

WEEKLY UPDATE 6/25 – 7/1/2018

6/25 – 7/1/18 ›

High count for the week of about 6,960 individual Caspian terns with an estimated 4,900 attended tern nests on the East Sand Island tern colony, lower than estimates from the previous week (7,660 individuals and 5,600 nests); the estimated number of tern chicks (3,800) on the East Sand tern colony this week was similar to the estimate the previous week (3,900 chicks); the majority of tern chicks on-colony are in the mid-sized stage of development; as was the case last week, the tern colony was comparatively undisturbed by bald eagles this week, with only two major disturbance events recorded; as a consequence, the rate of tern egg and chick losses to gull predation was low compared to earlier in the breeding season; in addition to the terns on the designated one-acre colony area, on average about 390 individual Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island

6/25 – 7/1/18 ›

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 7-8 times per day this week; a total of about 290 tern nest scrapes were discovered on the upper beach and filled-in this week, compared to about 170 tern nest scrapes the previous week; seven intact tern eggs were discovered outside the main colony area this week, compared to five eggs the previous week; to date, no tern eggs laid outside the one-acre designated colony area have persisted, and most are believed to have been depredated by gulls soon after laying

6/25 – 7/1/18 ›

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 11 disturbances (mostly minor) caused by bald eagles this week, compared to 7 total eagle disturbances to the colony the previous week; six adult gulls, one adult double-crested cormorant, and numerous gull and tern chicks were depredated and discovered on the east beach near the tern colony this week; fresh mink 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 6/18 – 6/24/2018

6/21/18 ›

Aerial survey of the Columbia River estuary, Willapa Bay, and Grays Harbor to search for nesting Caspian terns at sites other than the managed colony on East Sand Island; in the Columbia River estuary, 490 terns were seen attempting to nest on Rice Island and no terns were observed on the Tongue Point piers (40 terns seen on previous aerial survey on 5/20); in Grays Harbor, about 90 terns were seen loafing on No Name Island; appreciable numbers of terns (nesting or loafing) were not observed elsewhere during this survey, with the exception of East Sand Island

6/18 – 6/24/18 ›

High count for the week of about 7,660 individual Caspian terns on the East Sand Island tern colony, similar to the high count the previous week (7,640 individuals); estimates of the numbers of attended Caspian tern nests (5,600) and tern chicks (3,900) on the East Sand tern colony were somewhat higher this week compared to the previous week (4,800 nests and 2,500 chicks); the majority of tern chicks on-colony are in the recently-hatched to midsize stage of development; the tern colony was comparatively undisturbed by bald eagles this week, with only one major disturbance event recorded; as a consequence, the rate of tern egg and chick losses to gull predation was quite low compared to previous weeks; in addition to the terns on the designated one-acre colony area, on average about 350 individual Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island

6/18 – 6/24/18 ›

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 7-8 times per day this week; a total of about 170 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 130 tern nest scrapes found and filled-in the previous week; five intact tern eggs were discovered outside the main colony area this week, compared to one egg the previous week; to date, no tern eggs laid outside the one-acre designated colony area have persisted, and most are believed to have been depredated by gulls soon after laying

6/18 – 6/24/18 ›

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 7 disturbances caused by bald eagles this week, compared to 24 total eagle disturbances to the colony the previous week; fresh mink 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 6/11 – 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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