ACR Heron and Egret Project (HEP) 2018 Season

Dear Friends,

Here it is once again, our annual call to “get HEP!” To all new and returning volunteers, thank you so much for contributing your time and expertise to the 29th season of ACR’s Heron and Egret Project. Together we continue to expand our rich, decades‐long data set that is put into action each year to increase our understanding of the natural world and promote its conservation.

Last year we were pleased to tell you about the new Heron and Egret Telemetry Project. Led by Scott Jennings and David Lumpkin, we had a successful first year—safely tagging three adult Great Egrets. You can follow along as we observe the highly‐detailed log of their movements right here: https://www.egret.org/heron‐egret‐telemetry‐project. Coupled with the detailed reproductive information that you collect at each nesting site, these GPS data will help us improve our understanding of the roles herons and egrets play in the wetland ecosystem and how their habitat needs affect population dynamics. Ultimately, we hope these findings will inform conservation efforts and inspire generations of people to value these beautiful birds and the wetlands that sustain us all.

As most of you already know, this is John Kelly’s last year as Director of Conservation Science at Audubon Canyon Ranch. Though it is difficult to imagine life at the Cypress Grove Research Center without John’s intelligent leadership, fierce conservation ethic, and kind support, we are all very grateful for the time he has given this organization and look forward to hearing about his new adventures. Keep your eyes open for a future invitation (coming this summer) to a Cypress Grove Research Volunteer get‐together to celebrate John.

And now, let’s get ready for the 2018 monitoring season!

The contents of this orientation packet are edited yearly so please review the enclosed materials carefully. All of these items are also available for download from our project website.

This document contains the following:

1. 2018 Instructions for Field Observers 2. 2018 Preliminary List of Site Coordinators and Observers 3. Colony site visit forms and Season Summary Form 4. Heron and Egret Courtship Behaviors Fact Sheet 5. Heron and Egret Fact Sheet

Don’t forget, we have lots of other project related information for you to peruse on the Heron and Egret Project website, such as popular and scientific press articles, training materials, and fieldwork forms. Find the website here: https://egret.org/north‐bay‐nest‐monitoring.

Important Note:  The quality of your data is directly related to the number and duration of your site visits.  If you cannot observe your site during a regional observation period, please contact us in advance.

Finally, always remember: Our first concern is for the birds. Be cautious. Watch for alert postures when you approach a colony and retreat if there is any such suggestion of disturbance. Herons and Egrets are especially sensitive to disturbance early in the season. Our best approach is to treat these beautiful birds with cautious respect.

Your first observation period is March 2‐4, so please plan your visit now. If you have any questions please call, email, or text. We are happy to talk about the project with you at any time. We are looking forward to another a great Photo by Len Blumin season!

All the best,

Emiko Condeso John Kelly Ecologist/GIS Specialist Director of Conservation Science

Martin Griffin Preserve ∙ Bouverie Preserve ∙ Cypress Grove Research Center Modini Mayacamas Preserves 4900 Shoreline Highway One ∙ Stinson Beach, CA 94970 Email: [email protected] ∙ Website: www.egret.org ∙ Phone: 415.868.9244 2018 INSTRUCTIONS FOR FIELD OBSERVERS Audubon Canyon Ranch North Bay Heron and Egret Project 2018 REGIONAL OBSERVATION PERIODS DATES RESEARCH OBJECTIVE  Draw a panoramic sketch of the nesting trees. Locate and number all active nests on the March 2–4 sketch. (Fri ‐ Sun)  Determine the total number of active nests in the colony for each species.  Identify and monitor focal nests for each species. Please note this visit is now one of our required observation periods. March 17‐19  Determine the total number of active nests in the colony for each species. (Sat ‐ Mon)  Add additional focal nests as soon as they are confirmed to be active. It is important to begin tracking nest survivorship as early as possible.  Determine the total number of active nests in the colony for each species. April 6–8  Continue to add focal nests. Focal nests known to be active for less than two weeks can be (Fri ‐ Sun) added until the colony reaches its peak size.  Monitor focal nests. May 5–7  Determine the total number of active nests in the colony for each species. (Sat ‐ Mon)  Monitor focal nests. June 1–3  Determine the total number of active nests in the colony for each species. (Fri ‐ Sun)  Monitor focal nests. This visit may not be necessary if your site only has Great Blue Herons. June 23–25  Determine the total number of active nests in the colony for each species. (Sat ‐ Mon)  Monitor focal nests. ADDITIONAL OBSERVATION PERIODS For sites with Snowy Egrets, Cattle Egrets, and Black-crowned Night-Herons Snowy Egrets, Cattle Egrets, and Black-crowned Night-Herons are able to leave the nest platform 10-14 days after hatching. Because of this, weekly visits greatly enhance the accuracy of our estimates of reproductive success. If you are observing a colony with Snowy Egrets, Cattle Egrets, and/or Black-crowned Night-Herons, we encourage you to check in on your focal nests on a weekly basis. Please let us know if this is not possible for you. Site coordinators should contact us immediately if any of these species are new to your site this year.

PLEASE PLAN YOUR FIELD TIME:

 Check the Preliminary List of Site Coordinators and Observers for your colony assignment(s). Let us know as soon as possible if we need to make any changes to your assignment or if you need contact information for your partners.  If you are a Site Coordinator, it is your responsibility to inform other field observers about access requirements and to coordinate team or individual observations. The Site Coordinator compiles the data at the end of the season and submits them to the Cypress Grove Research Center.  Plan to visit your site once during each of the Regional Observation Periods above. If you cannot observe your site during a scheduled Observation Period, please call Cypress Grove Research Center as soon as possible. Standardized Regional Observation Periods allow us to compare reproductive timing among colonies. These dates provide the minimum four site visits required for this study. However, additional visits will greatly improve the quality of your data.  Arrange for the use of a telescope. Telescopes are necessary to obtain adequate data and will greatly add to your pleasure in viewing heron and egret behavior. We encourage you to acquire your own scope; however a few telescopes are available for loan from the Cypress Grove Research Center. Contact us as early as possible to arrange to borrow one.

(Continued…)

HOW TO SET UP YOUR MONITORING PROGRAM:

1. DETERMINE THE NUMBER OF ACTIVE NESTS EARLY IN THE SEASON. What is an active nest? We define a nest to be “active” when evidence of a pair bond has been observed. Determine this by looking for the following: before April 1st, either two adults present on the same nest platform or one adult carrying nest material or incubating. After April 1st, any occupied nest is “active.” Please note: Black-crowned Night- Herons may engage in nest building before pair bond formation. Therefore, one adult carrying nest material alone does not indicate an active nest. For Black-crowned Night-Herons, please look for at least one of the following: two adults present on the same nest platform, a stick presentation, a nest with eggs or chicks, or a single adult on a well–constructed nest platform (sturdy enough to hold at least two eggs).

2. COMPLETE A NESTING PANORAMA. The nesting panorama is a landscape sketch or photograph that indicates the location of numbered nests you will follow through the season. Additional sketches or photos may be needed if you view numbered nests from different vantage points. Remember to check all sides of nesting trees. Excellent panoramas can be created by making enlarged photocopies of photographs. If you use panoramas from previous years, re-number nests to reflect the current colony.

3. SELECT FOCAL NESTS. Focal nests are used to measure the rate of nest survival by monitoring them repeatedly through the entire season. As early as possible, try to identify a minimum of 15 focal nests per species. A “focal nest” must be observed “active” either before Stage 1, or at Stage 1. New focal nests known to be active for less than two weeks can be added until the colony reaches its peak size.

If your colony has 15 or fewer active nests, or if you commit to monitor every nest in the colony, then all nests that meet the above criteria are focal nests. Try to record a complete row of data for each focal nest on every visit, even if you no longer see activity in a nest. If your colony has more than 15 active nests and you cannot monitor every nest on every visit, select a random subset of nests for each species to monitor as focal nests. To select a random subset of nests, write each nest number on a separate slip of paper and place in a paper bag. Select at least 15 nest numbers from the bag for each species.

Obtaining complete data for every focal nest is crucial, and will determine the length of time necessary for a complete visit. Observations during feeding and nest relief provide the best opportunity for complete data. If you have any questions, please call us!

“FOCAL NEST” is “STAGES” are defined defined in Step 3, on the Colony Visit above. Form

Re‐number nests on “ACTIVE NEST” is Check this Box if you are confident you’ve counted all your panorama each defined in chicks in the nest. This may be impossible when year. Step 1, above. chicks are young, but please make a special effort to count all chicks in Stage 4 nests.

Focal (A) Active # # Comments: Nest # Species nest? (P) Possible Adults Stage Chicks behavior, feeding, (I) Inactive nest relief, food, etc. 1 GBHE A / P / I 1 4 2 Feeding obs.; parent left colony after 12 min. 2 GBHE A / P / I 1 3 3 Nest partly obscured by foliage 3 GBHE A / P / I 0 4 3 Lost chick; 4 chicks on April 10 4 GBHE A / P / I 1 Possible new attempt after failure ? Will recheck 5 GBHE A / P / I 0 0 Failed last visit (April 10) 6 GBHE A / P / I 0 4 3 IMPORTANT: The data on nest #6 was not focal, but please report # chicks in all Stage 4 nests, even if they were not monitored on previous visits or assigned a nest number.

2018 Preliminary* List of Site Coordinators and Observers

Please check for your name and let us know if we need to make any changes!

 If you would like to make any changes to your assignment or need contact information for your partners please call Emiko at (415) 663‐8203 x401.  The observer listed in bold is the site coordinator. If you have any questions about what is required or do not wish to be a coordinator, please call us. If you are the only observer at a site—congratulations, you are the site coordinator!  Note that only sites that require volunteer observers in 2018 are listed here. There are other active heronries in the Bay Area—if you are curious about them let me know.

*For a continuously updated list of observers, please see https://egret.org/observer‐roster

Site Name County Observers Alcatraz Island San Francisco Brianne Brussee (BCNH, SNEG), Victoria Seher (any other study species present) Bel Marin Keys Marin Janet Bodle, VOLUNTEER NEEDED Bell Canyon Reservoir Napa Ellen Sabine, Greg Raynor Blake's Landing South Marin VOLUNTEER NEEDED Bodega Bay Flat Road Sonoma Ann Cassidy, Lauren Hammack Campbell Ranch Sites Solano VOLUNTEER NEEDED Chalk Hill Road Sonoma VOLUNTEER NEEDED Chiles Creek Sites Napa Nancy Abreu Cloverdale, River Road Sonoma Janet Bosshard Congress Valley Napa Denice Britton, VOLUNTEER NEEDED Cypress Road Marin Barbara Wechsberg, Steve Hadland DeSilva Island Marin Madelon Halpern, Ron Brown, Ron Mallory Dover Park Solano Kate Keiser, Joanne Castro Fitch Mountain North Sonoma Kate Symonds Fox Ridge Road Sonoma VOLUNTEER NEEDED Freezeout Road Sonoma VOLUNTEER NEEDED Gold Hill Solano VOLUNTEER NEEDED Hagen Road Napa Penny Proteau Inverness Park North Marin Joan Lamphier Laguna de Santa Rosa sites (Alpha, Laguna, Delta, Sonoma Denise Cadman Meadowlane Ponds) Lake Berryessa Sites Napa Todd Eggert Lake Herman Solano Wally Neville Lake Nicasio Marin Ann Linder, Bob Battagin Las Gallinas Marin Daniel Edelstein Mare Island Sites Solano Wally Neville, Robin Leong Marin Islands Marin John Kelly, Binny Fischer North San Pedro Road 2 Marin Janet Bodle Oddfellows Sonoma Nina Madrid

Site Name County Observers Petaluma Wastewater Plant Sonoma Len Nelson, Sheryl Nadeau, Deb Sheppard Pope Valley 2 Napa Bill Bridges (with Phil Burton, as available) Raccoon Straits and Raccoon Straits Ridge Marin Patti Blumin, Sylvie Silverstein Riverfront Park Sonoma Patrick Woodworth San Pablo Dam Sites Contra Costa Phoebe Tanner, Julie Roemer Seminary Marin Madelon Halpern, Ron Brown Skaggs Island Sites Napa Meg Marriott South Kelly Napa Kathy Hageman Tree Farm Marin Tom Baty Via Palo Linda Solano Joanna Castaneda Vigilante Road Sonoma Kathleen Mugele, Gerry Mugele West 9th and Blair Sonoma David Lumpkin (SNEG, CAEG, BCNH), Brett Lane (GREG) Willota Drive Solano Joanna Castaneda

HERON COLONY SITE VISIT FORM (side 1) Audubon Canyon Ranch—Cypress Grove Research Center

PLEASE USE A SEPARATE FORM FOR EVERY VISIT. DO NOT SUMMARIZE VISITS HERE.

Colony Site: Date of visit (mo/day/year): Observer(s): Start time: End time: Visibility of nests (glare, wind, rain, or other interference):

Please use Species Codes: GBHE (Great Blue Heron) GREG (Great Egret) SNEG (Snowy Egret) BCNH (Black-crowned Night-Heron) CAEG (Cattle Egret) DCCO (Double-crested Cormorant)

COUNT ALL ACTIVE NESTS FOR EACH SPECIES. Active nests include all focal nests and other occupied nests that meet the following criteria:  Before April 1st, ACTIVE NEST must have either two adults present on the same nest platform or one adult carrying nest material or incubating.  After April 1st, any occupied nest is ACTIVE. For Black‐crowned Night‐Herons only, an active nest meets at least one of the following criteria:  Two adults present on a single nest platform;  An adult placing a stick presented to it by another adult (as in a stick presentation ceremony);  Nest contents (eggs or chicks);  A single adult on a well‐constructed nest platform (sturdy enough to hold at least two eggs).

GBHE GREG SNEG BCNH CAEG DCCO ACTIVE NESTS POSSIBLY ACTIVE (Before April 1st only)

Notes: Please describe unusual behaviors, signs of disturbance, food scraps under nests, known feeding areas, etc.

Nest predatory species □ Common Raven □ Great Horned Owl □ Red‐Tailed Hawk present within 100 m of colony site: □ Other ______□ Other ______□ Other ______

PLEASE ENTER INDIVIDUAL NEST DATA ON THE OTHER SIDE.

At the end of the season, duplicate all field forms before sending data, season summary form, and panoramic photos to: ACR’s Cypress Grove Research Center, P.O. Box 808, Marshall, CA 94940; (415) 663‐8203; [email protected] HERON COLONY SITE VISIT FORM (side 2) COLONY SITE: ______DATE (mo/day/year): ______

Nesting Stage: 1 = Egg laying, incubation, adult lying down for long periods, egg turning, defecation, nest relief. 2 = Hatching, small (downy) chicks, feeding low in the nest, watch carefully when adults move. 3 = Chicks (usually) standing; most/all down replaced by juvenal plumage; at least one parent continuously at nest. 4 = Adults not continuously at nest (may remain after feeding); chicks (usually) on nest platform. 5 = Young often off nest. Record the number of chicks and duration of time they are off the nest.

Check box if this is a Check box if you are confident of the Focal Nest chick count

(A)ctive Comments on nest activity: nest location notes, displays, copulation, nest Nest Species # Nest # (P)ossible building, hatching, chick size, feedings, nest relief, nest failure, re‐nests, # Code Adults Stage Chicks (I)nactive disturbance type and result, change in species, etc. 1 □ A / P / I □ 2 □ A / P / I □ 3 □ A / P / I □ 4 □ A / P / I □ 5 □ A / P / I □ 6 □ A / P / I □ 7 □ A / P / I □ 8 □ A / P / I □ 9 □ A / P / I □ 10 □ A / P / I □ 11 □ A / P / I □ 12 □ A / P / I □ 13 □ A / P / I □ 14 □ A / P / I □ 15 □ A / P / I □ 16 □ A / P / I □ 17 □ A / P / I □ 18 □ A / P / I □ 19 □ A / P / I □ 20 □ A / P / I □ 21 □ A / P / I □ 22 □ A / P / I □ 23 □ A / P / I □ 24 □ A / P / I □ 25 □ A / P / I □ 26 □ A / P / I □ 27 □ A / P / I □ 28 □ A / P / I □ 29 □ A / P / I □ 30 □ A / P / I □ At the end of the season, duplicate all field forms before sending data, season summary form, and panoramic photos to: ACR’s Cypress Grove Research Center, P.O. Box 808, Marshall, CA 94940; (415) 663‐8203; [email protected] (ACR USE ONLY) Screener Initials:

Heron and Egret Project Please complete a separate Season Season Summary Form Summary Form for Audubon Canyon Ranch Cypress Grove Research Center each species. (415) 663-8203, [email protected]

Year: Colony Name/Number: Species (please circle one): GBHE GREG SNEG CAEG BCNH DCCO Observers (circle your name): Total Observation Days: Total Observation Hours:

Nest totals (focal + all other nests) Observation Date (month/day) __/__ __/__ __/__ __/__ __/__ __/__ __/__ __/__ __/__ __/__ Total Active Nests

Total Possibly Active Nests

Number of nests at each stage (focal + all other nests) Observation Date (month/day) __/__ __/__ __/__ __/__ __/__ __/__ __/__ __/__ __/__ __/__ # nests at Stage 1 # nests at Stage 2 # nests at Stage 3 # nests at Stage 4 # nests at Stage 5

Number of Stage 4 nests (focal + all other nests)

with a brood with a brood with a brood with a brood with a brood Only include nests size of 1 size of 2 size of 3 size of 4 size of 5 where the entire brood was visible (no hidden Note: Use the brood size at Stage 4 for each of your nests regardless of nestlings). visit date. If a nest is observed at Stage 4 on multiple visits, use the brood size from the latest visit. (continued) Please mail all materials to: The Cypress Grove Research Center, P.O. Box 808, Marshall, CA 94940 HEP Season Summary form (side 2) Colony Name:______Year:______Species:______

Enter focal nest data only in this section. Number of focal nest failures

Total number of focal nests = (see Instructions For Field Observers)

Visit date when failure detected (month/day)

__/__ __/__ __/__ __/__ __/__ __/__ __/__ __/__ __/__ __/__ Number of focal nest failures

Total number of focal nest failures = (should equal total of failures listed above)

Disturbance to colony Attach additional pages if needed.

ACR USE ONLY Date Observed Description Type Result (month/day) or Inferred Please describe evidence of colony disturbance in Code1 Code2 (O/I) detail. Include source (if known) and any observed response by herons and/or egrets.

1 A=avian, H=human, W=weather, M=mammal, O=observer, P=unknown predator, U=unknown 2 1=behavioral response, 2=nest failure, 3=colony abandonment, 4=pre-season disturbance, prior to arrival

Nest Predatory Species

Present within 100 m of colony site Check box if nesting Common Raven □ □ Great Horned Owl □ □ Red-Tailed Hawk □ □ Bald Eagle □ □ Other (please specify): □ □

Please mail all materials to: The Cypress Grove Research Center, P.O. Box 808, Marshall, CA 94940 HERON & EGRET COURTSHIP BEHAVIOR

BEHAVIOR DESCRIPTION SIGNIFICANCE

Stretch Lifts head and closes bill Typical courtship display to vertical (GBHE may howl accentuates plumes: often at peak). The head is then as part of greeting ceremony. brought down with lateral swaying and bent legs.

Snap Moves head forward and Typical display used in diff‐ down, neck extended, then erent contexts, usually not snaps bill shut, usually directed to anyone: General with legs bent. May be advertisement. done in conjunction with Stretch.

Twig Shake Slowly extends neck, grasps General advertisement. twig with bill and shakes. Resembles nest building behavior.

Arched Neck Erect neck feathers and Usually used by moving heron head plumes, curves neck as threat display. with bill downward.

Upright Neck Bill up, neck extended. Antagonistic or threat display.

Crest Raising Erect head plumes. Common threat display.

Forward Lifts wings, retracts head Antagonistic or territorial and rocks forward, stabbing display, sometimes used by toward another bird. Rapid young chicks in nest. tail‐flicking in egrets.

Circle Flights Flies in large circle with Used in identification and neck extended, returning appeasement. to original perch.

Landing Calls Given when landing on nest, Recognition, pair‐bonding. as part of Greeting Ceremony.

(Continued…)

HERON & EGRET COURTSHIP BEHAVIOR

BEHAVIOR DESCRIPTION SIGNIFICANCE

Supplanting Aerial display; flies at Aggressive display, may end other perched bird and in fight. lands on its vacated perch.

Bill Duels By newly paired birds, male Strengthens pair‐bonding. stabs at relatively sub‐ missive female. Eventually decreases intensity as toler‐ ance develops. Female may hold the male’s bill.

Bill Clappering Rapid chattering of bill Maintains close, un‐aggressive with or without contact contact with mate. with other bird.

Wing Preen Moves bill along primaries Pair‐bonding, un‐aggressive as if preening, but does close contact. not touch feathers. Orients towards male.

Greeting General term for behaviors Recognition, strengthens pair Ceremonies when bird returns to nest bond. and mate. May include Landing call, Stretch and Bill Clappering.

These behaviors generally occur in specific stages:

 Unpaired males do Snap and Stretch displays (general advertisements), along with aggressive behaviors (Supplanting, Arched and Upright Neck).  When a potential mate arrives, displays change to Wing Preen, Bill Clappering, and Stretch.  The intial paired stage includes Bill Duels and more Bill Clappering.  Once the pair‐bond is established, Greeting Ceremonies occur such as Landing Call, Stretch and Bill Clappering.  Greeting Ceremonies continue through incubation and parental stages.

HERON AND EGRET FACT SHEET

Great Blue Herons and Great Egrets By Helen Pratt

Great Blue Herons and Great Egrets are long-legged, long-necked birds adapted for wading in shallow water such as lake edges, marshes and tidal flats and for capturing fish, frogs, small crustaceans and other aquatic prey. They also sometimes hunt for small rodents, grasshoppers, snakes and lizards in grassy fields.

The Great Blue Heron is the largest North American wading bird. It stands up to 4 feet tall, weighs about 5 pounds, and has a wing span of 6 feet. In spite of its name, it looks grey under most viewing conditions. But when seen in flight from above, if the light is right, the wing feathers take on a bluish cast.

The Great Egret weighs about 2 pounds and has a wing span of 4 1/2 feet. It is all white and is distinguished by long plumes or "aigrettes" that grow from the shoulder and can be elevated and spread fan-shaped during pair formation displays.

The herons begin to occupy the nesting area at Audubon Canyon Ranch and throughout the Bay Area in late January or early February. Egg laying generally starts in late February or early March and peaks sometime in March.

The egrets are more variable in their arrival dates than the herons. They usually arrive in mid-March and start laying in the fourth week of March, but they have arrived as late as the second week in April. Their laying peak is sometime in April.

Both species lay 2-5 greenish-blue eggs. Heron eggs are about as big around as a large chicken egg but they are longer and somewhat more pointed. Egret eggs are proportioned like heron eggs but they are a little smaller. At Audubon Canyon Ranch, 3 egg clutches are the most common for both species. They lay their eggs at 2-3 day intervals.

Incubation starts sometime between laying of the first and second egg. The adults alternate in incubating, and the first egg hatches in from 25-29 days, usually between 27 and 28 days. The second egg hatches within 24 hours of the first and the succeeding eggs hatch at 2 to 3 day intervals depending on the laying interval.

Chicks of both species are sparsely covered with down on hatching. Heron chicks are grey, egret chicks are white.

Both parents feed the young. Heron parents feed their chicks about 4 times during the daylight hours. They may also bring food to the young once or twice during the night. Egret parents feed their chicks 3 or 4 times during the day but probably not during the night.

(Continued…) During incubation and for the first 3 weeks after hatching an adult is always present at the nest. When the chicks are between 3 and 4 weeks of age, the nest is sometimes unattended by an adult, and after the chicks are 4 weeks old, the adults are at the nest only long enough to feed the young.

Both species feed their newly hatched young by regurgitating food into the nest and the chicks pick it up and gulp it down. As the chicks increase in size and strength they seize their parents' bills on their own at feeding time and try to pull them down into the nest perhaps hoping to hasten the delivery of food. After egret chicks are large enough to grasp their parents' bills in this way, food goes directly into the mouths of the young instead of being deposited in the nests. Food for young herons continues to be dropped into the nest until they reach independence.

Not all chicks survive to independence. In broods of 3 or 4, the chicks that hatch later are smaller and weaker than their older nest mates. Older chicks aggressively peck the younger ones at feeding time and force them away from the food. When the adults bring plenty of food all the chicks in the brood survive, but if food is limited, the younger chicks die. Successful adults usually raise 2 young, sometimes 3 and rarely 4.

Heron young take their first long flight at about the age of 8 weeks but usually remain at the nest and are fed by the parents for 2 or 3 weeks longer. Egret young are able to fly at about 7 weeks of age but usually do not leave the nest until they are 10-12 weeks old.

We don't know where the birds from Audubon Canyon Ranch go when they leave the colony. Members of the heron family are noted for extended post-breeding dispersal especially among the young. Recent evidence suggests that the Great Blue Herons spend their winter scattered throughout the bay area. Young Great Egrets may fly south some perhaps as far as Mexico or Central America, but the adults probably winter closer to the colony.

Mortality of the young in the first months after leaving the nest is high. Estimates for Great Blue Heron mortality during the first year range from 65-76% although Bayer found that mortality for nestlings banded at National Wildlife Refuges in the west was only 33%. He suggested that fledglings from these refuges suffered less harassment. A study of Great Egret mortality found that 76% of the fledglings died in their first year. After the first year, mortality declines for birds of both species to around 36% in the second year and 22% each year afterward. Some individuals can live a long time. The oldest heron recovery on record was 23 years of age and an egret was recovered at age 22.

Black-crowned Night-Herons, Snowy Egrets, and Cattle Egrets (from The Birds of North America series, issues 74, 489, and 113)

Black-crowned Night-Herons are a cosmopolitan species that breeds on every continent except Australia and Antarctica. As they are nocturnal, usually feeding from evening to early morning in shallow ponds, creeks and marshes. During the breeding season, birds also feed during the day to meet the extra food demand of their young.

Black-crowned Night-Herons are medium sized, with a stocky build and relatively short neck and legs. Both males and females have a distinctive black cap and back, with gray wings and body. The bill is predominantly black and the eyes are red. Legs are yellow for most of the year, but become pink at the height of the breeding season. Juvenile birds are brown with white spots above and pale below with striped underparts.

Breeding is initiated when males select nest sites and advertise for females. Black-crowned Night-herons may choose to nest in many different substrates, including trees, shrubs, and marsh reeds. Males may engage in light nest building before pair formation. The first egg is usually laid 4- 5 days after pair formation and additional eggs are laid at 2 day intervals. Both parents incubate and hatching occurs in 23-26 days. By 12 days post-hatch, both parents are actively foraging most of the day. Both parents feed the young at the nest; chicks are fed mostly fish, but also amphibians, crustaceans, insects, and other nestlings.

Young are fed by regurgitation, which is initially given directly to young chicks, and later delivered into the nest cup. Young can leave the nest platform in 12-14 days and can fly 6 weeks post-hatch. Black-crowned Night-Herons usually have one brood per season, though they will re- nest if the initial nest fails.

Snowy Egrets are one of our most beautiful egrets--their delicate back plumes were once highly prized for use in ladies hats. Snowy Egrets have apparently made a remarkable recovery from a severe reduction in population size due to plume hunting in the late 1800s-early 1900s. Despite this comeback, Snowies are still a species of concern, as they are particularly sensitive to factors that influence prey density and availability such as wetland destruction and fragmentation.

Snowy Egrets are medium sized, with all white plumage, black bill, black legs, and bright yellow feet. Immature and nonbreeding adults have duller greenish-yellow feet. Adults in breeding plumage develop long plumes on the lower back and breast. The bright yellow skin of the lores and feet turn red at the height of breeding.

Snowy Egrets may take a wide variety of prey items, including worms, insects, crustaceans, amphibians, and fish; however studies have shown their actual diet to be somewhat specialized, composed of about 75% fish and 25% crustaceans. They generally prefer to feed in shallow, brackish habitats.

(Continued…)

Breeding is initiated when males select nest sites and advertise for females. The usual clutch size is 3-5 eggs; both sexes incubate. Hatching occurs in 20-21 days. Both parents feed chicks. Chicks are capable of leaving the nest as early as 10 days old, but are known to stay close to the nest site until 6-7 weeks of age. Snowy Egrets usually have one brood per season, though they will re- nest if the initial nest fails.

Cattle Egrets are well-known for their association with lawns, fields, and pastures. The range of cattle egrets expanded to include the continental United States in the 1950s. Cattle Egrets are stocky, whitish with a buff colored head, and have a short-necked appearance. Nonbreeding birds have yellow bill, lores, and irises, and greenish-yellow legs. During the breeding season they develop orange-buff colored plumes on head, lower back, and chest. At the height of breeding, legs, bill, and iris become red, and lores purple-pink.

Cattle Egrets have a broad diet that is mostly grasshoppers, crickets, moths, and fish taken in shallow water. Birds will nest in trees, shrubs, or reeds. Average clutch size is 3-4 eggs. Both sexes incubate eggs, and hatching occurs in 22-25 days. At 14 days post-hatch chicks frequently leave the nest but remain nearby to be fed. Chicks can fly at 25 days post hatch. Cattle Egrets generally have one brood per season, but like our other species of herons and egrets, will re-nest if the initial nest fails.