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

Columbia River Estuary

Weekly Update for 5/11 – 5/17/2015

 

5/11 – 5/17/15 ›

 

High count for the week of an estimated 7,630 Caspian terns on East Sand Island tern colony, higher than the estimated high count for the previous week (6,160); numbers of Caspian terns counted off-colony remained high this past week, with 900-1,500 terns regularly seen loafing on the east beaches; in general, the tern colony appeared to be more settled this week as compared to previous weeks, with terns being less susceptible to disturbance and flushing less frequently from the colony; three Caspian terns that were satellite-tagged on Crescent Island on the mid-Columbia River earlier this season remained on the East Sand Island tern colony this week, all three attending nests with eggs until one satellite-tagged tern lost its eggs to gull predation on 11 May

 

5/11 – 5/17/15 ›

 

Corps’ contractors (LKE) continued monitoring Caspian tern nest dissuasion areas at the east and west ends of East Sand Island; ca. 500 Caspian terns continue to roost adjacent to nest dissuasion materials (ropes, stakes, and flagging) above the waterline on the upper southeast beach, adjacent to the Caspian tern colony; ca. 100 terns and 40 attended tern nests are now located underneath nest dissuasion materials in this area; a minimum of five Caspian terns eggs were laid in off-colony areas on East Sand Island this week, three of which were subsequently depredated by gulls

 

5/11 – 5/17/15 ›

 

Signs of multiple predators observed on East Sand Island; no signs of disturbance or predation by great horned owls at the Caspian tern colony for the second consecutive week; bald eagles and peregrine falcons continue to cause disturbance to nesting Caspian terns and gulls on the east end of the island; fresh river otter tracks and, for the first time this season, raccoon tracks were observed on the south beach

 

5/14/15 ›

 

Second ground-based survey of Rice Island to resight banded Caspian terns; ca. 265 Caspian terns were seen on the west end of Rice Island, one group of ca. 150 terns on fresh dredged material that was deposited on the island in 2014, and another group of ca. 115 terns adjacent to the area of fresh dredged material; a total of 16 banded Caspian terns were resighted on Rice Island, only 5 of which had been resighted earlier this season on East Sand Island.

 

Weekly Update for 5/4 – 5/10/2015

 

5/4 – 5/10/15 ›

 

High count for the week of an estimated 6,100 Caspian terns on East Sand Island tern colony, slightly higher than the estimated high count for the previous week (5,900); an increase in average Caspian tern nesting density on the tern colony was observed this week compared to the previous week; associated with higher nesting densities in core areas of the colony more Caspian terns have been setting up nest territories at the periphery of the colony, where gull depredation rates are higher than in the core; nest chronology on the tern colony is highly asynchronous, with the outer edges and western portion of the colony experiencing higher rates of egg loss due to intense predation pressure from gulls; three Caspian terns that were satellite-tagged on Crescent Island on the mid-Columbia River earlier this year were resighted on the East Sand Island tern colony attending nests with eggs

 

5/4 – 5/10/15 ›

 

Corps’ contractors (LKE) continued monitoring Caspian tern nest dissuasion areas at the east and west ends of East Sand Island; ca. 500 Caspian terns continue to roost adjacent to nest dissuasion materials (ropes, stakes, and flagging) above the waterline on the upper southeast beach, adjacent to the Caspian tern colony; at least six pairs of terns have moved underneath nest dissuasion materials and are sitting in nest scrapes; terns in this area are frequently disturbed by bald eagles and peregrine falcons, and part of the area will likely become inundated during upcoming high high tide events, but some Caspian tern nests initiated in this area outside the 1-acre managed colony area may persist

 

5/4 – 5/10/15 ›

 

Signs of multiple predators observed on East Sand Island; no signs of disturbance or predation by great horned owls at the Caspian tern colony this week; frequent daytime bald eagle and peregrine falcon disturbances to nesting terns and gulls on the east end of the island and roosting California brown pelicans on the southeast beach; these disturbances cause Caspian terns to flush from their nests, which allows glaucous-winged/western gulls to depredate tern eggs from unattended nests; there has been a recent lull in bald eagle visits to the Caspian tern colony during evening twilight, disturbances that cause large numbers of tern eggs to be depredated by gulls; fresh river otter tracks seen on the south beach

 

5/8/15 ›

 

First boat-based survey of roosting California brown pelicans conducted at East Sand Island; ca. 950 brown pelicans counted, nearly all on the south beach at the east end of the island, near the Caspian tern colony

 

5/7/15 ›

 

First ground-based survey of Rice Island to resight banded Caspian terns; ca. 900 Caspian terns and ca. 400 tern nest scrapes counted on dredge spoil that was deposited in 2014 on the former colony site used by Caspian terns in the late 1990s; no Caspian tern eggs were observed

 

Weekly Update for 4/27 – 5/3/2015

 

4/27 – 5/3/15 ›

 

High count for the week of an estimated 5,900 Caspian terns on East Sand Island tern colony, the same as the estimated high count for the previous week; an increase in tern nesting activity was observed compared to the previous week; nest chronology on the tern colony is highly asynchronous, with the outer edges and western portion of the colony experiencing high rates of egg loss due to gull depredation; three terns that were satellite-tagged on Crescent Island on the mid-Columbia River earlier this year were resighted on the East Sand Island tern colony attempting to initiate nests this week

 

4/27 – 5/3/15 ›

 

Corps’ contractors (LKE) continued monitoring Caspian tern nest dissuasion areas at the east and west ends of East Sand Island; ca. 500 Caspian terns were observed roosting between dissuasion (ropes, stakes, and flagging) and at the waterline on the upper southeast beach adjacent to the Caspian tern colony; about 20-30 terns were observed digging nest scrapes and sitting in incubating posture in this area; terns in this area are frequently disturbed by bald eagles and peregrine falcons, and the area will likely become inundated during upcoming high high tide events, so tern nests initiated in this area may not to persist

 

4/27 – 5/3/15 ›

 

Several hundred California brown pelicans are now roosting on the southeast beach at East Sand Island

 

4/27 – 5/3/15 ›

 

Signs of multiple predators observed on East Sand Island; no signs of disturbance or predation by great horned owls at the tern colony this week; frequent bald eagle disturbance to the tern colony continued this week, causing terns to flush from their nests and allowing glaucous-winged/western gulls to depredate tern eggs from unattended nests; fresh river otter tracks seen on the north and south beaches

 

Weekly Update FOR 4/20 – 4/26/2015

 

4/25/15 ›

 

First aerial survey of Columbia River estuary (CRE), Willapa Bay, and Grays Harbor; main objective of flight was to detect the possible formation of new Caspian tern colonies; ca. 400 Caspian terns observed sitting, scraping, and copulating on new dredge deposits at the west end of Rice Island (CRE); ca. 200 Caspian terns seen roosting on the Tongue Point piers (CRE); all other terns observed in the CRE were at multiple roost locations below the high tide line; 100’s of Caspian terns were also observed roosting below the high tide line on Whitcomb Flats, Cate Island, and Sand Island in Grays Harbor; American white pelicans were observed nesting once again on Miller Sands Spit (CRE), with 261 adult pelicans and 144 attended pelican nests counted

 

4/22/15 ›

 

First Caspian tern eggs (3) observed on East Sand Island tern colony; all three eggs depredated by glaucous-winged/western gulls during a colony-wide disturbance shortly thereafter

 

4/20 – 4/26/15 ›

 

High count for the week of an estimated 5,900 Caspian terns on East Sand Island tern colony; terns nesting on the east-central part of the colony area are more settled and further along in nest chronology compared to terns nesting on the western part of the colony, apparently due to higher disturbance rates in the western part of the colony by a great horned owl; egg-laying by terns increased as the week progressed; however, most tern eggs on colony were subsequently depredated by gulls during evening disturbances to the colony; glaucous-winged/western gulls depredate most of the tern eggs laid on colony during these disturbances; three nesting pairs of glaucous-winged/western gulls have set up breeding territories on the southern edge of the tern colony, preventing terns from nesting in the surrounding area; in addition to the terns nesting on colony, ca. 1,000 Caspian terns were regularly seen loafing on beaches that surround East Sand Island

 

4/15 – 4/20/15 ›

 

The ring-billed gull colony is once again forming in an upland area at the northeast tip of East Sand Island; some individuals are on completed nests in incubating posture, suggesting that egg-laying has commenced

 

4/14 – 4/20/15 ›

 

Signs of multiple predators observed on East Sand Island; great horned owl continues to cause major disturbance 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 increased this week, causing terns to flush from the colony up to 4-5 times per hour around sunset; fresh river otter tracks seen on the north and south beaches

 

WEEKLY Update FOR 4/13 – 4/19/2015 

 

4/17/15 ›

 

Additional silt fencing was erected to further reduce the Caspian tern colony area on East Sand Island down to 1.0 acre

 

4/17/15 ›

 

Corps contractors (LKE) began monitoring of Caspian tern nest dissuasion areas at the east and west ends of East Sand Island

 

4/14/15 ›

 

Colony monitors moved out to East Sand Island and began continuous monitoring of the Caspian tern breeding colony

 

4/13 – 4/19/15 ›

 

Small groups of California brown pelicans are starting to arrive at East Sand Island; up to 50 California brown pelicans seen roosting on the south beach

 

4/13 – 4/19/15 ›

 

High count for the week of an estimated 4,900 Caspian terns on East Sand Island tern colony; in addition, ca. 2,500 Caspian terns regularly seen loafing on beaches that surround East Sand Island

 

4/13 – 4/19/15 ›

 

Signs of multiple predators observed on East Sand Island; as many as 15 bald eagles observed on the island at one time; great horned owl caused major disturbance to nesting Caspian terns each night from 4/17 to 4/19 and an owl was observed killing and eating an adult tern on colony on 4/18; peregrine falcons and bald eagles caused repeated disturbances to the tern colony during daylight hours all week; fresh river otter tracks seen daily on the north and south beaches

 

Update FOR 3/16 – 4/12/2015 

 

4/11/15 ›

 

First California brown pelicans (150) observed on East Sand Island (loafing on south beach)

 

4/6 – 4/12/15 ›

 

Conducted colony preparations on the East Sand Island tern colony; field crew erected observation blinds and above-ground tunnels, set up camp, laid out colony grids, spread PIT tags for detection efficiency studies, placed photo monuments for analysis of aerial photography, and deployed tern decoys on core tern colony area; Corps contractor (LKE) tilled and harrowed 1.3 acres of the tern colony area, removed and repaired damaged silt fencing around the tern colony area, placed tern dissuasion (ropes and flagging) outside the 1.3-acre colony area, on both the east end and the west end of East Sand Island, where Caspian terns have prospected for nest sites in previous years

 

4/6/15 ›

 

First California brown pelicans sighted in Columbia River estuary by project staff in 2015; four seen in the water off the southeast tip of East Sand Island; no pelicans were seen on East Sand Island

 

4/4/15 ›

 

First Caspian terns (98) observed on East Sand Island tern colony

 

3/28/15 ›

 

First Caspian terns (15) observed on East Sand Island (loafing on east beach)

 

3/21/15 ›

 

First Caspian tern sighted in Columbia River estuary by project staff in 2015; one tern seen flying over East Sand Island

 

3/16 – 4/12/15 ›

 

Signs of multiple predators observed on East Sand Island; as many as 15 bald eagles observed on the island at one time; great horned owl flushed from a tree on the north beach on 3/26 and a fresh owl pellet was found near an observation blind at the edge of the tern colony on 4/6; avian predator, likely a bald eagle, killed a Caspian tern on north edge of the tern colony on 4/7; fresh river otter tracks seen daily on the northeast beach

 

3/16/15 ›

 

Seasonal field crew began work in Columbia River estuary; first visit to East Sand Island to assess the condition of the Caspian tern nesting area; shoreline erosion on the south side of tern colony has resulted in loss of silt fencing; vegetation has grown in between existing silt fence rows, rendering those areas unsuitable for tern nesting; European beach grass has encroached into the core tern colony area reducing the available nesting habitat below what was available in 2014 (1.55 acres); strong winter storms have caused significant wind transport of nesting substrate (sand) from the east end to the west end of the tern colony; no terns present on island; thousands of glaucous-winged/western gulls were establishing nesting territories near the tern colony and elsewhere on the island

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

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