Swainson’s Hawk Program

Swainson’s Hawk Program

The Swainson’s hawk (Buteo swainsoni) is a state-listed threatened species in California that was listed in 1983 by the California Fish and Game Commission due to its diminishing habitat and the decreased population numbers across the state.  Today, the majority of the population in California resides throughout much of the California Central Valley that extends from Tehama County to Tulare and Kings Counties.  However, the population core is located within portions of Yolo, Solano, Sacramento, and San Joaquin Counties, which provides the most optimum foraging habitat and nesting conditions for the hawks.  The City of Elk Grove (City) lies within the core area that provides suitable Swainson’s hawk habitat consisting of large, open grassland and agricultural landscapes.  Historically, Swainson’s hawks foraged in the agricultural lands in and around Elk Grove.

Swainson’s Hawk Distribution in the California Central Valley

Map Source: The Distribution, Abundance, and Habitat Associations of the Swainson’s Hawk in the City of Elk Grove, January 2009.

Swainson’s Hawk Characteristics

The Swainson's hawk is characterized by its long, narrow, and tapered wings held in flight in a slight dihedral shape while the bird is in flight. The most distinctive identifying feature of adults is the dark head and breast band that is distinctive from the lighter colored belly, and the underside of the wing with the linings lighter than the dark gray flight feathers.  Adult females weigh between 900 and 1100 grams (32 to 39 oz), and males from 800 to 1000 grams (28 to 35 oz).


Swainson’s Hawk in Flight

Swainson’s hawks are migratory birds of prey that spend their breeding season (roughly March 15th thru September 15th) in the Central Valley and their winters on the plains of southern Brazil and Argentina.  Their migratory route can be as long as 14,000 miles; lasting at least two months to make the long distance flight. Certain types of agricultural crops and pastures provide excellent foraging habitat for Swainson’s Hawks, especially crops that support large insects, such as grasshoppers, or small mammals such as meadow voles and mice.  Crops or grazing regimes that expose prey to aerial predation is the preferred foraging habitat.  Typical Swainson’s Hawks’ agricultural foraging areas include alfalfa, irrigated pasture, dryland pasture, and some low-growing row crops such as tomatoes, beans, beets, etc.  Grain fields such as wheat and oats are also known to serve as important cover types for foraging Swainson’s Hawks after they are harvested. Crops such as corn, rice, sunflower, safflower, orchards, or vineyards are not considered suitable as foraging habitat.  Swainson’s hawks typically hunt in flight or from perches located near foraging areas.  Sight is the primary means of detecting prey so low-growing vegetation or sparsely vegetated areas typically exposes prey to the hawks more easily than dense or tall growing vegetation.  Typical flood irrigation can also benefit the hawks by forcing small mammals and insects to retreat from their hiding places.

Typical Central Valley Swainson’s Hawk Foraging Habitat

Elk Grove Swainson’s Hawk Mitigation

As agricultural lands converted to urban development in Elk Grove, the hawk’s foraging habitat was equally being displaced.  Following the vision of the citizens in Elk Grove, one of the City’s General Plan guiding goals is the protection of the natural environment.  To implement this goal, the General Plan contains policies aimed at protecting the City’s natural resources, which would include the loss of Swainson’s hawk foraging habitat.

In 2003, the City established and adopted Chapter 16.130 (Swainson’s Hawk Impact Mitigation Fees) of the Elk Grove Municipal Code, which establishes mitigation policies tailored for projects in Elk Grove that have been determined through the California Environmental Quality Act (CEQA) process to result in a “potential significant impact” on Swainson’s hawk foraging habitat.  Chapter 16.130, often referred as the “Swainson’s Hawk Code,” serves as a conservation strategy that is achieved through the selection of appropriate replacement lands and through management of suitable habitat value on those lands in perpetuity.  To mitigate for the loss of foraging habitat in the City, the Swainson’s Hawk Code allows a project applicant to provide mitigation by one or a combination of the following options:

  1. Provide direct land preservation to the City by fee title or conservation easement on a per acre basis (one-to one mitigation ratio), including an endowment for easement monitoring.  Interests in mitigation lands are to be held in trust by an entity acceptable to the City and/or the City in perpetuity.
  2. Pay Swainson’s Hawk impact mitigation fee on a per acre basis of habitat impacted.  The current fee is $9,646 per acre, which the City utilizes the fees collected to mitigate the project’s impacts by acquiring land in fee title and/or conservation easements on suitable Swainson’s hawk foraging habitat.  Although the Swainson’s Hawk Code states that the payment of a mitigation fee is limited to projects less than 40 acres, the City Council has lifted the restriction in the interim to allow projects 40 acres and over the option to pay the mitigation fee.
  3. Purchase mitigation credits at an accredited mitigation bank that is acceptable to the City and California Department of Fish and Game.
  4. Purchase credits from a property owner with eligible credits for projects in Elk Grove that is acceptable to the City and California Department of Fish and Game.
  5. Provide other instruments to preserve suitable habitat as determined by the California Department of Fish and Game.

Conservation Easement Lands and Delta Breeze Property

The City has received and currently holds a total of seven conservation easements as a form of Swainson’s hawk mitigation for projects occurring in Elk Grove.  As mentioned, direct land preservation by conservation easement is allowed as a mitigation option with the establishment of an associated endowment to cover the cost of monitoring.  The conservation easements that the City has accepted are dispersed throughout southern Sacramento County in areas that would ensure the maximum benefit to the Swainson’s hawk by maintaining habitat connectivity with adjacent open foraging habitat lands, which together provides regional hawk population stability – see map below for easement locations.  The conservation easements are in perpetuity and the City conducts annual monitoring for all easements to ensure that the conservation easement restrictions are enforced – the link to the conservation easement annual reports are available in the table below.

In addition to the conservation easements, the City purchased two parcels totaling 743 acres in 2005 at the southwest corner of Franklin Boulevard and Lambert Road.  The purpose of the purchase was to satisfy the City’s obligation of acquiring suitable Swainson’s hawk foraging habitat lands for projects mitigating by paying the Swainson’s hawk mitigation fee.  The mitigation property, known as the “Delta Breeze Property,” is currently managed by the U.S. Bureau of Land Management (BLM) in association with the Cosumnes River Preserve.  The BLM currently manages several agricultural leases as part of their on-going operations at the Preserve. The BLM will manage the Delta Breeze Property consistent with the terms and conditions of the Conservation Easement and the Preserve’s March 2008 Final Management Plan (found at www.cosumnes.org).

In 2009, a conservation easement was placed on 736 acres of the 743-acre Delta Breeze Property and transferred along with an endowment to the Nature Conservancy.  This easement ensures that the Property will be managed as agricultural land and for the benefit of the Swainson’s hawk in perpetuity.  Currently, the property is leased to a local farmer and farmed in a manner that is consistent with the conservation easement.

The table below lists the City-held conservation easements, which additional information for each easement may be obtained by clicking on the “Fact Sheet” label for the respective easement property.  In addition, the annual easement monitoring reports for each City-held conservation easement are available for viewing by clicking on the reporting year (except Delta Breeze Property).  As the conservation easement for the Delta Breeze Property is held by The Nature Conservancy, the annual reporting of the Delta Breeze Property will be included as part of the reporting program established for the Cosumnes River Preserve.  However, the grant deed establishing the conservation easement on the Delta Breeze Property may be viewed by clicking on the “Grant Deed for Conservation Easement” under the Delta Breeze easement heading in the table below.

Swainson’s Hawk Habitat Conservation Easements

Easement Property Easement Acreage(1) Location Fact Sheet Easement Monitoring Report
Acterra 91.8 South end of Stone Lake Rd. and east of I-5 Fact Sheet 2009
2010
2011
2012
Carli 150.21 1-mile SW of Grant Line Rd. Fact Sheet 2009
2010
2011
2012
Delta Breeze 736.6 SW corner of Franklin Blvd. & Lambert Rd. Fact Sheet Grant Deed for Conservation Easement
Goodwin-Gwerder 80 South of Kost Rd. and .5 mile east of Orr Rd. Fact Sheet 2009
2010
2011
2012
Kirkham 169 SW corner of Twin Cities Rd. & Franklin Blvd. Fact Sheet 2009
2010
2011
2012
Mahon 62.35 South of the Grant Line Rd. & Waterman Rd. intersection Fact Sheet 2010
2011
2012
Mohamed 80 Southeast of the Grant Line Rd. & Wilton Rd. intersection Fact Sheet 2009
2010
2011
2012
Pennisi 90.8 NW corner of Franklin Blvd. & Twin Cities Rd. N/A N/A
Reynen & Bardis 14.75 East of the Grant Line Rd. & Freeman Rd. intersection Fact Sheet 2009
2010
2011
2012
(1) Easement acreage may just be a portion of the total parcel size.

Swainson’s Hawk Studies

In order to obtain better information regarding hawk nesting and foraging sites, the City funded a baseline survey in 2006 to provide the City with a more complete understanding of the distribution and population of Swainson’s hawks in south Sacramento County.  A subsequent report on the Swainson’s hawk population in south Sacramento County was released in 2009 that provided results from the continuation of on-going data collection and field work to evaluate the City’s Swainson’s hawk mitigation strategy.  In order to provide additional information on Swainson’s hawk nesting distribution and abundance within the Elk Grove city limit, a survey was conducted in 2008 with the final report released in 2009.  All three reports are available for review below by clicking on the selected report.

Questions & Answers

What is the species status of the Swainson’s hawk and why do these impacts need to be mitigated?

In California, the Swainson’s hawk was listed as a threatened species in 1983 by the California Fish and Game Commission.  As such, it is protected by the California Endangered Species Act (CESA), which prohibits the “take” of any endangered or threatened species. Take is defined in Section 86 of the Fish and Game Code as "hunt, pursue, catch, capture, or kill, or attempt to hunt, pursue, catch, capture, or kill."Thus, the loss of critical habitat for an endangered or threatened species also constitutes a take. The species is also protected by the California Environmental Quality Act (CEQA). Under CEQA, the loss of habitat for a threatened or endangered species is considered a significant adverse effect. CEQA states that projects should not be approved if there are feasible mitigation measures available to reduce a significant adverse effect to a less than significant level. The City, acting as a Lead Agency under CEQA, in consultation with the California State Department of Fish and Game (DFG), a responsible agency under CEQA, has determined that adverse effects to Swainson’s hawk foraging habitat can be mitigated to a less than significant level.

Protecting a threatened species’ foraging habitat follows the vision of the citizens of Elk Grove. One of the City’s General Plan guiding goals is the protection of the natural environment, which the General Plan contains policies aimed at protecting the City’s natural resources. Mitigating for the loss of Swainson’s hawk foraging habitat is consistent with these policies and ensures the long-term viability of this species in and around the City, for the enjoyment of Elk Grove’s future generations. 

How are impacts to Swainson’s hawk foraging habitat mitigated?

The Department of Fish and Game has determined that the loss of foraging habitat can be mitigated to an acceptable level by permanently preserving suitable foraging habitat. Based on DFG guidelines, the City has established the Swainson’s Hawk Code (Chapter 16.130 of the Municipal Code), which establishes that projects 40 acres and greater must mitigate by direct preservation of land at a 1:1 ratio. Projects less than 40 acres are given the option to mitigate by payment of an in lieu fee at a 1:1: ratio. The funds are used by the City to find and preserve suitable Swainson’s hawk habitat.

Where is adequate mitigation found?

The purpose of mitigation in Elk Grove is to protect the population of hawks that nest in and around Elk Grove. According to ecological principles, protecting large, contiguous parcels is the most efficient approach for the long-term sustainability of natural resources. Alfalfa fields and row crops such as beet, and tomato, and cereal grain crops are considered suitable foraging habitat for the Swainson's hawk. In addition, based on the hawk’s foraging radius, the DFG has determined that impacts to Swainson's hawk foraging habitat should be mitigated within 10 miles from the project site. Therefore, ideal mitigation is agricultural lands of low growing row or field crops located within 10 miles of a project site, and in close proximity to other protected areas.

Why can’t we mitigate farther than 10 miles from a project site?

The 10-mile distance is a standard by the Department of Fish and Game based on the flight radius from an active nest and foraging habitat. In order to protect the population of Swainson’s hawks nesting in and around Elk Grove, land within its foraging radius should be preserved. In addition, mitigating farther than 10 miles from a project site could result in the protection of foraging grounds for a population of hawks that don’t necessarily nest in and around the City.

If there is Swainson's hawk habitat in the City of Elk Grove, why is mitigation not acceptable within city limits?

The Department of Fish and Game has determined that in order to ensure the long-term viability of this species, large, contiguous areas of protected lands are required. As the City builds out, the existing parcels with suitable habitat are expected to be surrounded by development making them unsuitable for foraging habitat. Consequently, mitigation within City limits would be unacceptable to the DFG because the City lacks land large enough to ensure the long-term viability of this species.

Staff Contact

Gerald Park, Senior Planner
8401 Laguna Palms Way
Elk Grove, CA 95758
(916) 478-3671

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