Bank Swallow Conservation in California
Beverley A. Anderson1, Adam Henderson1, Ronald E. Melcer Jr.2, andDanika C. Tsao3
California Department of Water Resources
1Division of Integrated Regional Water Management, Northern Region Office. 2400 Main Street, Red Bluff, Ca, U.S.A;
2FloodSAFE Environmental Stewardship and Statewide Resources Office, 9th Street, Sacramento, Ca , U.S.A;
3Division of Environmental Services. 3500 Industrial Boulevard, West Sacramento, Ca, U.S.A.
Bank Swallow Status
- The Bank Swallow (Ripariariparia; BANS) is a California State Threatened species that depends on natural riverine process to create and maintain its nesting habitat.
- Within California, >70% of the remaining BANS population nests in the eroding banks of the Sacramento River and its tributaries (Figure 1).
- IMPACTS AND THREATS
- The primary threat to
- BANS is loss of nesting
- habitat through flood
- control and bank
- armoring projects.
- Federal (USACE) and
- State (DWR) project rip-
- rap and private revetment
- activities have armored
- approximately 25% of banks between Red Bluff and Colusa (Figure 2).
- CONSERVATION OPPORTUNITIES
- DWR has a significant opportunity to protect and recover the Bank Swallow through the protection and restoration of fluvial processes and floodplain connectivity through FloodSAFE activities.
- As an active partner of the Bank Swallow Technical Advisory Committee (BANS TAC), DWR is working with CDFG, USFWS, USACE, TNC, River Partners, PRBO, and others to conduct monitoring, research, and conservation planning in order to ensure the persistence of the Bank Swallow in California.
- BANS TAC members have conducted annual population surveys along the Sacramento River since 1986. DWR scientists have participated in these surveys, and included surveys along the Feather River for5years.
- Results of these surveys provide abundance and distribution information that help assess the status of Bank Swallows in California. More recent surveys have also included habitat assessment information
- Colonies are mapped using an
- onboard GIS. Burrow counts are
- recorded along with habitat data
- such as bank height and vegetation
- above the bank.
- Surveys to date have shown a decline in the Bank Swallow population, and a need for more active protection and restoration of their nesting habitat
- (Figure 3).
- QA/QC of Historic Data
- The BANS TAC has worked with graduate student researchers and recently partnered with the US Amy Corps of Engineers to digitize and verify historic datasets. These efforts provide an understanding of colony locations and long-term population estimates from 1986-1999. Data from 1999 to present have been error-checked (Figure 4).
- The BANS TAC is developing a Conservation Strategy for the Bank Swallow.
- The strategy will include a summary of life history requirements and ecology, sensitivities and threats, and provide specific recommendations regarding the management, conservation, and recovery of the species through river management activities, including:
- Avoidance of Impacts by using alternatives to bank stabilization, setbacks, and acquiring easements to allow erosion
- Protection of Existing Colonies and Habitat by acquisition of property or easements on land with existing colonies or that support natural river processes
- Restoration of Habitat and Natural River Processes by using setback levees or rock removal
- Mitigation of Unavoidable Impacts of rock placement by rock removal
- Once completed, the Conservation Strategy will be submitted to CDFG for adoption
Figure 4. Bank Swallow burrow counts from 1986 to 2012. Data from 1986 to 1999 have not undergone QC, so numbers cannot be included in analysis of long-term population trends. Red line shows 3 year moving average.
Bank Swallow (Riparia riparia)
- Methodology Studies
- DWR scientists have assisted in a study to verify burrow count assumptions. This work will lead to greater confidence in annual estimates of population size.
Figure 1. Historic and current distribution of BANS nesting sites within California.
Location where private rock was bypassed by the river to expose a newly eroded bank. Bank Swallows used this area for nesting the season following “removal”
Bank revetment has negatively impacted bank swallow nesting habitat a) Arundodonaxplanted in front of an eroding bank b) Agency rock placed over an eroding bank previously used by BANS.
Bank Swallow burrows on an eroding bank below an orchard with an easement to allow erosion
- Burrow Occupancy
- The BANS TAC
- has evaluated the occupancy rate of burrows in active colonies in order
- to estimate the number of pairs
- from annual
- burrow count data.
Figure 2. Extent of rip-rap on the upper Sacramento River as of 2002.
- Soils Assessment
- The BANS TAC worked with
- USDA soil scientist Dean
- Burkett to investigate soils
- along the Sacramento River
- and determine preferred soil
- texture for BANS burrows.
- This information may assist
- with locating potential
- restoration sites.
Figure 3. The number of Bank Swallow pairs and cumulative length of rock revetment along reaches 2 and 3 of the Sacramento River.
- Funding provided by US Army Corps of Engineers and DWR FESSRO.
- BANS-TAC partners: R. Martin, M. Bradbury (DWR); D. Wright, K. Barker, G. Ford (CDFG); J. Silveira (USFWS); G. Golet (TNC); N. Seavy (PRBO); B. Luke (USACE); D. Garcia (Altacal Audubon); Michael Rogner (River Partners).
Yellow oval indicates soils in areas used by BANS; blue rectangle indicates soils in areas not used by BANS.