Weekly Update for 8/17 – 8/23/2009
8/20 – 8/22/09 ›
Substrate samples were processed at the Brooks Island Caspian tern colony to recover coded-wire tags from juvenile salmonids tagged and released in the San Francisco Bay area; this was our final visit for research purposes to Brooks Island and other Caspian tern colonies in the San Francisco Bay area for 2009
Weekly Update for 8/10 – 8/16/2009
Nothing to report
Weekly Update for 8/3 – 8/9/2009
8/3/09 ›
Substrate samples collected from Eden Landing E-10 tern colony; samples will be searched for coded-wire tags from juvenile salmonids tagged and released in the San Francisco Bay area
Weekly Update for 7/27 – 8/2/2009
7/29/09 ›
Substrate samples collected from Stevens Creek (B2) tern colony; samples will be searched for coded-wire tags from juvenile salmonids tagged and released in the San Francisco Bay area
Weekly Update for 7/20 – 7/26/2009
7/22/09 ›
With the exception of coded-wire tag recovery, regular colony monitoring in the San Francisco Bay Area has ended for the 2009 breeding season
Weekly Update for 7/13 – 7/19/2009
7/13 – 7/19/09 ›
Average colony attendance at the Stevens Creek (B10) tern colony reached its peak in mid-May and steadily declined until mid-June; since then colony attendance has stabilized or increased in some weeks, presumably due to an influx of subadults and failed breeders from other tern colonies in the region
Weekly Update for 7/6 – 7/12/2009
7/6 – 7/12/09 ›
For the first week this nesting season, no juvenile salmonids were found in bill loads of Caspian terns nesting at the Brooks Island colony
7/11/09 ›
Tracks on Brooks Island indicated that someone dragged a kayak through the main Caspian tern colony to get across the spit; the lowest count of Caspian terns at the main colony this week (55 terns) was observed on the same date
7/7/09 ›
Survey of Agua Vista Park Caspian tern colony; 21 adult Caspian terns and one tern fledgling observed
Weekly Update for 6/29 – 7/5/2009
7/3/09 ›
Fireworks display carried out 600-700 meters to the north of the Brooks Island tern colony caused 95% of the nesting and roosting terns to leave the island for up to 3 minutes; three other disturbances were noted at the tern colony during the fireworks display, none were as severe as the first; no brown pelicans were on Brooks Island at the time of the fireworks display
6/29/09 ›
First Caspian tern fledgling observed on Stevens Creek (B10) tern colony
Weekly Update for 6/22 – 6/28/2009
6/22 – 6/28/09 ›
All 36 radio-tagged Caspian terns that were previously nesting on Brooks Island have failed, presumably due to high gull predation rates on tern eggs and chicks at the colony
6/24/09 ›
67 Caspian tern chicks captured and banded at the Brooks Island tern colony; Steve Bobzien (East Bay Regional Parks), Cory Overton (USGS), Jeff Lewis (USGS), Karen Peluso (Marine Sciences Institute), Wesley Gray (SFBBO), Elizabeth Robertson (SFBBO), Jocelyn Davidson (SFBBO), Caroline Thow (SFBBO), Jonathon Shore (Common Murre Restoration Project), Celeste Dodge, and Steve Tucker assisted with chick banding at Brooks Island
6/24/09 ›
First Caspian tern fledgling observed on Brooks Island tern colony
6/24/09 ›
54 brown pelicans roosting on Brooks Island
6/21 – 6/24/09 ›
High high tide events caused some flooding on the Brooks Island Caspian tern colony; no nest failure was recorded
6/23/09 ›
30 Caspian tern chicks captured and banded at the Eden Landing (E10) tern colony; Cheryl Strong (USFWS), Christine Schukraft (USFWS), Ryan Randall (USFWS), Lisa Eigner (Common Murre Restoration Project), and Adam St. Savior (OSU-Fisheries) assisted with chick banding at Eden Landing (E10)
6/22/09 ›
Aerial photo census to estimate number of fledgling Caspian terns produced on Brooks Island tern colony
Weekly Update for 6/15 – 6/21/2009
6/15 – 6/21/09 ›
The proportion of salmonids in the diet of Brooks Island Caspian terns declined sharply for the second straight week; salmonids comprised 36.0%, 6.9%, and 0.9%, respectively, of prey items during the last three weeks; the rapid decline of salmonids in the diet coincided with the cessation of releases of hatchery-reared juvenile salmonids from net pens in San Pablo Bay
6/16/09 ›
First Caspian tern fledgling observed on Eden Landing (E10) tern colony
Weekly Update for 6/8 – 6/14/2009
6/14/09 ›
The last aerial survey to locate radio-tagged Caspian terns (tagged on 12-13 May) was conducted; a total of 13 aerial surveys were conducted and 305 off-colony detections of 50 radio-tagged Caspian terns were collected
6/14/09 ›
An incipient Caspian tern colony at Redwood Shores near Redwood City, CA was visited; one adult Caspian tern and one tern chick were observed at the site
6/8 – 6/14/09 ›
The proportion of salmonids in the diet of Brooks Island Caspian terns declined precipitously from a high of 36% of prey items last week to 7% this week; the decline in the proportion of salmonids in the diet of Brooks Island terns was associated with the cessation of daily releases of hatchery-reared juvenile salmonids from net pens in San Pablo Bay
6/8 – 6/14/09 ›
The size of the Brooks Island Caspian tern colony declined by 20% during the past week; high gull predation rates on tern chicks in recent weeks is the major cause for the decline; high nest predation rates by gulls have not been observed at either the Eden Landing or Stevens Creek Caspian tern colonies so far this year
Weekly Update for 6/1 – 6/7/2009
6/1 – 6/7/09 ›
The proportion of salmonids in the diet of Brooks Island Caspian terns was 36% this week, the highest weekly percentage ever recorded at that colony; the vast majority of the smolts consumed by terns from this colony are hatchery-reared juvenile salmonids released from net pens in San Pablo Bay
6/1 – 6/7/09 ›
Gull predation on tern chicks and eggs at the Brooks Island Caspian tern colony has increased to very high rates; gull depredation of 52 tern chicks and 17 tern eggs was observed during the week
Weekly Update for 5/25 – 5/31/2009
5/31/09 ›
47 double-crested cormorants counted on or near electrical transmission towers located near Stevens Creek (B2); two cormorant nests have been rebuilt since the removal of nests on 5/27 (see below)
5/25 – 5/31/09 ›
43 radio-tagged Caspian terns (out of a total of 50 total, see below) were frequently detected on Brooks Island at night; 23 were known to be nesting on Brooks Island; these terns foraged at various locations both in and outside San Francisco Bay, but not in the south bay; average foraging trip duration of radio-tagged terns is longer this year compared to last year
5/27/09 ›
Workers for Pacific Gas and Electric removed double-crested cormorant nests from several electrical transmission towers located near Stevens Creek (B2); 16 cormorant nests were removed from one tower that was previously surveyed by our crew
Weekly Update for 5/18 – 5/24/2009
5/18 – 5/24/09 ›
Shift in diet of Caspian terns nesting on Brooks Island from primarily surfperch and silversides in previous weeks to salmonids (27.3%), herring/sardines (20.1%), and smelt (11.8%)
5/23/09 ›
A high high tide caused some nest failure (minimum of 4 nests) due to flooding on the Brooks Island Caspian tern colony
5/21/09 ›
First Caspian tern chick observed on Ravenswood tern colony; four black skimmers on island, one pair nesting
5/18/09 ›
14 brown pelicans roosting on Brooks Island
Weekly Update for 5/11 – 5/17/2009
5/17/09 ›
First Caspian tern chick (2-3 days old) observed on Stevens Creek (B2) tern colony
5/15/09 ›
First aerial survey to locate radio-tagged Caspian terns (tagged on 12-13 May) was conducted; 18 Caspian terns were located at off-colony foraging locations, the majority (11) were in San Pablo Bay
5/12 - 5/13/09 ›
Adult Caspian terns were captured, color-banded, and fitted with radio tags (50) at the Brooks Island tern colony; Stacy Moskal, Sarah Poitter, Kathleen Henderson, and Kristin Hirsch (USGS) assisted with the capture and radio-tagging of Caspian terns at Brooks Island
Weekly Update for 5/4 – 5/10/2009
5/4 - 5/10/09 ›
Gull depredation rates on Caspian tern eggs and chicks at Brooks Island and Stevens Creek (B2) tern colonies were unusually high; suggesting a shortage of alternative food sources for gulls in Bay Area
5/9/09 ›
Aerial photo census was conducted to estimate the number of breeding pairs on the Brooks Island Caspian tern colony
5/8/09 ›
First Caspian tern chick observed on Eden Landing (E10) tern colony
5/7/09 ›
First Caspian tern chick observed on Brooks Island tern colony
Weekly Update for 4/27 – 5/3/2009
4/30/09 ›
First Caspian terns observed on Ravenswood tern colony; a pair of terns was attending a nest
4/28/09 ›
California gulls have begun nesting adjacent to Stevens Creek (B2) tern colony
Weekly Update for 4/20 – 4/26/2009
4/24/09 ›
First Caspian tern egg observed on Stevens Creek (B2) tern colony
Weekly Update for 4/13 – 4/19/2009
4/15/09 ›
Small groups of double-crested cormorants and American white pelicans loafing at Eden Landing (E10) tern colony adjacent to nesting Caspian terns
Weekly Update for 4/6 – 4/12/2009
4/12/09 ›
First Caspian tern egg observed on Brooks Island tern colony
4/12/09 ›
First Caspian tern egg observed on Eden Landing (E10) tern colony
Weekly Update for 3/30 – 4/5/2009
4/1/09 ›
Completed construction of new blind at Stevens Creek (B2) Caspian tern colony
3/30/09 ›
First Caspian terns observed on Eden Landing (E10) tern colony
Weekly Update for 3/23 – 3/29/2009
3/23/09 ›
First Caspian terns observed on Stevens Creek (B2) tern colony
3/23/09 ›
First Caspian terns observed on Agua Vista Park tern colony
Weekly Update for 3/16 – 3/22/2009
3/17/09 ›
First Caspian terns observed on Brooks Island tern colony
3/16/09 ›
Coded wire tags spread on Eden Landing (E10) Caspian tern colony for detection efficiency studies
3/16/09 ›
First Caspian terns observed near Stevens Creek (B2) colony site
Weekly Update FOR 3/9 - 3/15/2009
3/14/09 ›
Completed construction of new blind and tunnels at Brooks Island Caspian tern colony
3/13/09 ›
Coded wire tags spread on Brooks Island Caspian tern colony for detection efficiency studies
3/11/09 ›
Completed colony preparations and construction of new blind at the Eden Landing (E10) Caspian tern colony
3/11/09 ›
First Caspian terns observed near Eden Landing (E10)
3/11/09 ›
First Caspian terns observed near Brooks Island
3/9/09 ›
Field crew began working in the San Francisco Bay Area
