Data Name (This will be the displayed title in Catalog)
Seabird diet and productivity - New England
Indicator Name (as exists in ecodata)
seabird_ne
Family (Which group is this indicator associated with?)
[ ] Oceanographic
[ ] Habitat
[ ] Lower trophic levels
[X] Megafauna
[ ] Social
[ ] Economic
Data Description
Common tern annual diet and productivity at seven Gulf of Maine colonies managed by the National Audubon Society’s Seabird Restoration Program
Introduction to Indicator (Please explain your indicator)
Seabird breeding colonies in the GOM are monitored and managed to promote recovery of formerly harvested species. Common terns are well-monitored and are considered good nearshore ecosystem indicators due to their wide distribution and generalist diet. Common terns breed on islands throughout the Gulf of Maine, feeding on a wide range of invertebrates and fish including Atlantic herring, juvenile (mainly white) hakes, and sand lance. As surface feeding birds, terns are sensitive to vertical distribution of prey as well as nearshore conditions in general, with a foraging distance of 10-20 km from a nesting colony.
Key Results and Visualization
GOM common tern average productivity (fledglings per nest) across 7 colonies has varied over time. The pattern is similar to that observed for fish condition (high before 2000, lower 2001-2009, higher/variable since 2010. Productivity is affected by both food and predation mortality. While data on predation is lacking, productivity lows in 2004-2006 were associated with euphausiids, and the 2018 productivity low with butterfish in tern diets. The presence of butterfish in tern diets reflects the extension of this warm water species into GOM. Due to their thin, deep body form, butterfish are often difficult for small seabird chicks to ingest and swallow, causing chicks to starve and/or parent birds to increase foraging effort. 2020 was a challenging year for terns raising chicks. While diet composition was similar to the long term average, the quantity of food readily available was apparently less than normal, particularly around the time of chick hatching. This may have been confounded by cold, wet weather when chicks would normally be close to fledging in mid-to-late July. Anecdotal observations showed that feeding rates were low at both those times.
Implications
Declining productivity across multiple common tern colonies in the Gulf of Maine may indicate changes in the distribution, quality, and quantity of prey over time.
Spatial Scale
Gulf of Maine coastal areas
Temporal Scale
Spring and summer seabird breeding season
Synthesis Theme
[X] Multiple System Drivers
[ ] Regime Shifts
[ ] Ecosystem Reorganization
Define Variables
Variable names include the code for the island, COTE (4 letter standard abbreviation for COmmon TErn), and either "Productivity" or a prey category.
Indicator Category
[X] Published Methods
[ ] Extensive analysis, not yet published
[X] Syntheses of published information
[ ] Database pull
[X] Database pull with analysis
[ ] Other
If other, please specify indicator category
No response
Data Contributors
Don Lyons, Steve Kress, Paula Shannon, Sue Schubel
Point(s) of Contact
Don Lyons, dlyons@audubon.org
Affiliation
National Audubon Society
Public Availability
Source data are NOT publicly available.
Accessibility and Constraints
Please email dlyons@audubon.org for further information and queries on this indicator source data.
Primary Contact
dlyons@audubon.org
Secondary Contact
No response
Data Name (This will be the displayed title in Catalog)
Seabird diet and productivity - New England
Indicator Name (as exists in ecodata)
seabird_ne
Family (Which group is this indicator associated with?)
Data Description
Common tern annual diet and productivity at seven Gulf of Maine colonies managed by the National Audubon Society’s Seabird Restoration Program
Introduction to Indicator (Please explain your indicator)
Seabird breeding colonies in the GOM are monitored and managed to promote recovery of formerly harvested species. Common terns are well-monitored and are considered good nearshore ecosystem indicators due to their wide distribution and generalist diet. Common terns breed on islands throughout the Gulf of Maine, feeding on a wide range of invertebrates and fish including Atlantic herring, juvenile (mainly white) hakes, and sand lance. As surface feeding birds, terns are sensitive to vertical distribution of prey as well as nearshore conditions in general, with a foraging distance of 10-20 km from a nesting colony.
Key Results and Visualization
GOM common tern average productivity (fledglings per nest) across 7 colonies has varied over time. The pattern is similar to that observed for fish condition (high before 2000, lower 2001-2009, higher/variable since 2010. Productivity is affected by both food and predation mortality. While data on predation is lacking, productivity lows in 2004-2006 were associated with euphausiids, and the 2018 productivity low with butterfish in tern diets. The presence of butterfish in tern diets reflects the extension of this warm water species into GOM. Due to their thin, deep body form, butterfish are often difficult for small seabird chicks to ingest and swallow, causing chicks to starve and/or parent birds to increase foraging effort. 2020 was a challenging year for terns raising chicks. While diet composition was similar to the long term average, the quantity of food readily available was apparently less than normal, particularly around the time of chick hatching. This may have been confounded by cold, wet weather when chicks would normally be close to fledging in mid-to-late July. Anecdotal observations showed that feeding rates were low at both those times.
Implications
Declining productivity across multiple common tern colonies in the Gulf of Maine may indicate changes in the distribution, quality, and quantity of prey over time.
Spatial Scale
Gulf of Maine coastal areas
Temporal Scale
Spring and summer seabird breeding season
Synthesis Theme
Define Variables
Variable names include the code for the island, COTE (4 letter standard abbreviation for COmmon TErn), and either "Productivity" or a prey category.
Indicator Category
If other, please specify indicator category
No response
Data Contributors
Don Lyons, Steve Kress, Paula Shannon, Sue Schubel
Point(s) of Contact
Don Lyons, dlyons@audubon.org
Affiliation
National Audubon Society
Public Availability
Source data are NOT publicly available.
Accessibility and Constraints
Please email dlyons@audubon.org for further information and queries on this indicator source data.