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

Columbia River Estuary

Weekly Update 5/15 – 5/21/2017

5/17/17 ›

Aerial survey of the Columbia River estuary, Willapa Bay, and Grays Harbor; other than at East Sand Island, significant numbers of Caspian terns were only observed at No-Name Island in Grays Harbor were 85 adults (a few that appeared to be initiating nesting) were counted; appreciable numbers of terns (nesting or roosting) were not observed elsewhere during this survey

5/20/17 ›

Second boat-based survey of roosting California brown pelicans conducted at East Sand Island this season; a total of 148 brown pelicans counted on the island, all of which were on the southeast tip of the island; no nesting behavior by brown pelicans has been observed on East Sand Island so far this season

5/15 – 5/21/17 ›

High count for the week of ca. 7,300 individual Caspian terns on the East Sand Island tern colony, higher than the estimated count the previous week (ca. 6,700); rate of egg-laying by terns on the colony continues to be high; tern egg losses due to gull depredation of tern eggs in unattended nests following frequent flushes of the tern colony by bald eagles was high initially and declined as the week progressed; although most terns attending active nests with eggs (minimum of 1,000 nests, up from ca. 500 active nests the previous week) are located near the center of the 1-acre colony area, numbers nests that retained eggs over consecutive days on the eastern and southern portions of the 1-acre area increased substantially from last week

5/15 – 5/21/17 ›

Monitoring continued at Caspian tern nest dissuasion areas outside the 1-acre colony area on the east end of East Sand Island; field crew conducted regular hazing (nearly continuous) of terns using the upper beaches on the east end of the island; high count of 38 tern nest scrapes (similar to the high count of 32 the previous week) discovered on the south beach this week; 15 tern eggs were laid in the tern nest dissuasion areas this week, and all were either depredated by gulls or washed away during high tide events; passive nest dissuasion materials were added in multiple areas this week; a total of 1,000-2,000 terns observed loafing on the beaches at the eastern end of the island each day this week

5/15 – 5/21/17 ›

Signs of multiple predators observed on East Sand Island; bald eagles continued to cause frequent disturbances to the tern colony that leads to gull depredation of tern eggs in unattended nests, although terns are beginning to guard their nests more aggressively; a family of 5 river otters were observed on the north beach this week, but the field crew has seen no evidence that otters are having an impact on nesting terns; an adult peregrine falcon was observed on the north beach

Weekly Update 5/8 – 5/14/2017

5/8 – 5/14/17 ›

High count for the week of an estimated 6,700 individual Caspian terns on the East Sand Island tern colony, similar to the estimated high count for the previous week (ca. 6,900); rate of egg-laying by terns has increased from the previous week, but tern egg losses have remained high due to gull depredation of tern eggs in unattended nests following frequent flushes of the tern colony by bald eagles and after heavy rains that caused colony flooding late in the week; most terns that remain on active nests with eggs (ca. 500 nests, some with two-egg clutches) are located near the center of the 1-acre colony area

5/8 – 5/14/17 ›

Monitoring continued at Caspian tern nest dissuasion areas on the east end of East Sand Island; field crew conducted regular hazing (6 times daily) of terns using the upper beaches on the east end of the island; high count of 32 tern nest scrapes (down from 43 the previous week) discovered on the south beach this week; one tern egg discovered in the tern nest dissuasion areas this week, and was presumably depredated by a gull or washed away during a high tide event; passive nest dissuasion materials were added in multiple areas this week; a total of 1,000-2,000 terns observed loafing on the beaches at the eastern end of the island (below the wrack line) each day this week

5/8 – 5/14/17 ›

Signs of multiple predators observed on East Sand Island; bald eagles continued to cause frequent disturbances to the tern colony that leads to gull depredation of tern eggs in unattended nests; river otter tracks were regularly observed on the north beach this week, but the field crew has seen no evidence that the otters are having an impact on nesting terns; five tern carcasses were found on beaches at the eastern end of the island this week and were attributed to avian predation

Weekly Update 5/1 – 5/7/2017

5/6/17 ›

First boat-based survey of roosting California brown pelicans conducted at East Sand Island this season; a total of 11 brown pelicans counted throughout the island, all of which were on the southeast tip of the island; no nesting behavior by brown pelicans has been observed on East Sand Island so far this season

5/1 – 5/7/17 ›

High count for the week of an estimated 6,900 individual Caspian terns on the East Sand Island tern colony, up from the estimated high count for the previous week (ca. 5,030); about 95% of the 1-acre core colony area is occupied by nesting and pre-nesting terns, with only the extreme western end of the colony area remaining unoccupied; rate of egg-laying by terns has increased from the previous week, but tern egg losses to gull predation during frequent bald eagle flushes of the tern colony have remained high, and very few tern eggs have persisted on-colony for more than 24 hours

5/1 – 5/7/17 ›

Monitoring continued at Caspian tern nest dissuasion areas on the east end of East Sand Island; field crew conducted regular hazing (6 times daily) of terns using the upper beaches on the east end of the island; high count of 43 tern nest scrapes discovered on the southeast beach this week; one tern egg discovered in the tern nest dissuasion areas this week, and was presumably depredated by a gull or washed away during a high tide event; passive nest dissuasion materials were added in the area where the tern egg was found; 1,000-2,000 terns observed loafing on the east beaches (below the wrack line) each day this week

5/1 – 5/7/17 ›

Signs of multiple predators observed on East Sand Island; bald eagles continued to cause frequent disturbances to the tern colony, with up to 5 colony flushes observed per hour; river otter tracks were regularly observed on the north beach this week, near an apparent otter den, but the field crew has seen no evidence that the otters are having an impact on nesting terns; a brown pelican was observed on the Caspian tern colony on Friday, 5/5, consuming tern eggs that it took from nests (three tern eggs were observed being consumed), as well as kleptoparasitizing bill-load fish from terns on-colony

Weekly Update 4/24 – 4/30/2017

4/27/17 ›

First Caspian tern egg (broken) observed on the 1-acre tern colony on East Sand Island; the egg had apparently been depredated by a gull

4/24 – 4/30/17 ›

High count for the week of an estimated 5,030 individual Caspian terns on the East Sand Island tern colony, up from the estimated high count for the previous week (ca. 4,230); about 90% of the 1-acre core colony area is occupied by nesting and pre-nesting terns, with only the extreme western end of the colony area remaining unoccupied; the east end of the 1-acre core colony area continues to be subject to flooding during heavy rain events

4/24 – 4/30/17 ›

Monitoring continued at Caspian tern nest dissuasion areas on the east end of East Sand Island; field crew conducted regular hazing (5-6 times daily) of terns using the upper beaches on the east end of the island; high count of 28 tern nest scrapes discovered on the southeast beach this week; no tern eggs discovered in the tern nest dissuasion areas this week

4/24 – 4/30/17 ›

Signs of multiple predators observed on East Sand Island; although no great horned owls or other nocturnal predators were observed this week, the tern colony was frequently disturbed at night, causing complete colony abandonment on two nights this week; it appears that colony abandonment is occurring on clear nights and not on cloudy nights; bald eagles continued to cause frequent disturbances to the tern colony, stealing fish from terns during flushing events; evidence of predation on adult terns by bald eagles and peregrine falcons on seen on east beach

Weekly Update 4/17 – 4/23/2017

4/18/17 ›

First California brown pelican sighted in Columbia River estuary by project staff in 2017; no pelicans were seen on East Sand Island

4/19/17 ›

First California brown pelican (1) observed on East Sand Island, a juvenile loafing on the east beach

4/21/17 ›

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

4/17 – 4/23/17 ›

High count for the week of an estimated 4,230 individual Caspian terns on East Sand Island tern colony, up from the estimated high count for the previous week (ca. 1,330); roughly 80% of the 1-acre core colony area is occupied by pre-nesting terns, with observations of nesting behaviors (i.e. digging nest scrapes, copulation, courtship feeding) increasing throughout the week; east end of 1-acre core colony area subject to flooding during heavy rain events

4/17 – 4/23/17 ›

Monitoring continued at Caspian tern nest dissuasion areas on the east end of East Sand Island; field crew conducted regular hazing (3-4 times daily) of terns using the upper beaches on the east end of the island

4/17 – 4/23/17 ›

Signs of multiple predators observed on East Sand Island; although the great horned owl was not observed this week, there were signs of owl predation on terns discovered during the week, likely causing overnight colony abandonment on 4/19 and 4/20; bald eagles and peregrine falcons observed daily, causing terns to flush from the colony regularly; fresh river otter tracks seen on the north beach; evidence of avian predation on adult terns and gulls seen on east beach

Update 3/10 – 4/16/2017

3/10/17 ›

Seasonal field crew began work on East Sand Island

3/27/17 ›

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

3/30/17 ›

First Caspian terns sighted in Columbia River estuary by project staff in 2017; two terns seen flying over East Sand Island

4/1/17 ›

First Caspian terns (12) observed on East Sand Island (loafing on the east beach)

4/11/17 ›

First Caspian terns (157) observed on East Sand Island tern colony

4/13/17 ›

Completed colony preparations on the East Sand Island tern colony; 1.0 acre of nesting habitat was prepared for Caspian terns; within that 1.0-acre colony area, only the vegetated areas were tilled and harrowed; a 105-meter long fence row was erected along the southern border of the prepared colony area and another 80-meter fence row was erected inside and parallel to the southern boundary fence to reduce the total amount of available tern nesting habitat to 1.0 acre; observation blinds and above-ground tunnels were repaired, rope grids were laid out on the tern colony as aids in monitoring the colony, and PIT tags were spread on the colony for detection efficiency studies

4/13/17 ›

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

4/16/17 ›

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

4/10 – 4/16/17 ›

High count for the week of an estimated 1,325 Caspian terns on East Sand Island tern colony; most of the terns observed on colony were loafing, while a small number of the birds were engaged in pre-nesting behaviors (i.e. digging nest scrapes, copulation); in addition, 400-500 Caspian terns were regularly seen loafing on beaches near the main colony area on East Sand Island

4/10 – 4/16/17 ›

Signs of multiple predators observed on East Sand Island; bald eagles, red-tailed hawks, and peregrine falcons were observed occasionally flying over island; fresh river otter tracks seen daily on the north and west beaches; evidence of avian predation on adult terns and gulls seen on the east beach

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

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