Garth Herring

Forster’s Tern Chick Survival in Response to a Managed Relocation of Predatory California Gulls

admin — Thu, 23 Nov 2017 00:21:53 +0000

Forster’s Tern Chick Survival in Response to a Managed Relocation of Predatory California Gulls admin Wed, 11/22/2017 - 16:21

Document Category

Scientific Reports

Author(s)

Date

2014

Summary

Gull populations can severely limit the productivity of waterbirds. Relocating gull colonies may reduce their effects on nearby breeding waterbirds, but there are few examples of this management strategy. We examined gull predation and survival of Forster’s tern (Sterna forsteri) chicks before (2010) and after (2011) the managed relocation of the largest California gull (Larus californicus) colony (24,000 adults) in San Francisco Bay, California. Overall, survival of radio-marked Forster’s tern chicks from hatching to fledging was 0.220.03 (meanSE), and daily survival rates increased with age. Gulls were the predominant predator of tern chicks, potentially causing 54% of chick deaths. Prior to the gull colony relocation, 56% of radio-marked and 20% of banded tern chicks from the nearest tern colony were recovered dead in the gull colony, compared to only 15% of radio-marked and 4% of banded chicks recovered dead from all other tern colonies. The managed relocation of the gull colony substantially increased tern chick survival (by 900%) in the nearby (<1 km) colony from 0.040.02 in 2010 to 0.400.12 in 2011 but not at the more distant (>3.8 km) reference tern colony (0.290.10 in 2010 and 0.250.09 in 2011). Among 19 tern nesting islands, fledging success was higher when gull abundance was lower at nearby colonies and when gull colonies were farther from the tern colony. Our results indicate that the managed relocation of gull colonies away from preferred nesting areas of sensitive waterbirds can improve local reproductive success, but this conservation strategy may shift gull predation pressure to other areas or species. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Keywords

Impact of Salt Ponds Restoration on California Gull Displacement and Predation on Breeding Waterbirds

admin — Thu, 23 Nov 2017 00:21:53 +0000

Impact of Salt Ponds Restoration on California Gull Displacement and Predation on Breeding Waterbirds admin Wed, 11/22/2017 - 16:21

Document Category

Scientific Reports

Author(s)

Caitlin W. Robinson-Nilsen

Date

2013-06-30

Summary

The California Gull (Larus californicus) population in the South San Francisco Bay has increased from fewer to 200 breeding Gulls in 1982, to a peak of 52,172 in 2012. Specific to this study there were 46,030 breeding Gulls in 2010 and 37,716 breeding Gulls in 2011.

Keywords

Response of Waterbird Breeding Effort, Nest Success, and Mercury Concentrations in Eggs and Fish to Wetland Management

admin — Thu, 23 Nov 2017 00:21:53 +0000

Response of Waterbird Breeding Effort, Nest Success, and Mercury Concentrations in Eggs and Fish to Wetland Management admin Wed, 11/22/2017 - 16:21

Document Category

Scientific Reports

Author(s)

Joshua T. Ackerman

Collin A. Eagles-Smith

Date

2010-12

Summary

In cooperation with the Don Edwards San Francisco Bay National Wildlife Refuge, we experimentally manipulated water levels in pond A12 to examine the response of waterbird breeding effort and nest success, and assess the unintended consequence of this management action on the bioaccumulation of methylmercury into bird eggs and fish. We compared results from pond A12 to adjacent reference ponds and marshes.

Keywords

birds

mercury

fish

Impact of Salt Pond Restoration on California Gull Displacement and Predation on Breeding Waterbirds - Annual Report 2010

admin — Thu, 23 Nov 2017 00:21:53 +0000

Impact of Salt Pond Restoration on California Gull Displacement and Predation on Breeding Waterbirds - Annual Report 2010 admin Wed, 11/22/2017 - 16:21

Document Category

Scientific Reports

Author(s)

Joshua T. Ackerman

Jill D. Bluso-Demers

Mark P. Herzog

Caitlin W. Robinson-Nilsen

Garth Herring

Date

2010-12

Summary

Our objectives are to determine the impact of gulls on breeding snowy plovers and Forster’s terns.; Color-mark California gulls at A6 to determine potential nesting distributions after restoration of A6.; Continue our California gull colony surveys to document current population size. Herein, we provide an update of fiscal expenditures and a summary of recent research findings as they pertain to the objectives of this project.

Keywords