CNDDB News Blog

Ardeidae is a family of wading birds that includes herons, egrets, and bitterns. These birds are often characterized by their long bills, necks, and legs. They forage predominantly on aquatic animals including amphibians, fish, crustaceans, and mollusks. Additionally, some birds can be found foraging for small mammals, reptiles, and insects in grassy fields.

When the breeding season arrives, most Ardeids, excluding bitterns, gather into colonies called rookeries or heronries. The males will begin nest building and displaying in attempt to attract a female. The birds will form monogamous pairs for the season and take turns incubating eggs, brooding chicks, and foraging. They can lay 2-7 eggs depending on the species. During feedings, nestlings compete for provisions brought in by the parents. In years when food is limited, competition among nestlings increases and can result in aggression and siblicide. Nestlings may also behave aggressively toward nestlings in adjacent nests.

One of our very own Environmental Scientists has been volunteering with the Audubon Canyon Ranch Heron and Egret Monitoring Project to assist in their effort to monitor Ardeid colonies in the Bay Area. At a snowy egret (SNEG, Egretta thula) and black-crowned night-heron (BCNH, Nycticorax nycticorax) rookery in a residential park in Fairfield, she monitors and records the heron behavior and nesting success on a weekly basis. The flexible branches of the nest trees and the high winds of Fairfield plus the aggressive nestling behavior result in numerous chicks falling from nests. The survivors get loaded into cat carriers by volunteers and are shuttled to International Bird Rescue in hopes that they will recover and return to the rookery next year.

California has seven native Ardeid species: great egret, snowy egret, great blue heron, black-crowned night-heron, green heron, American bittern, and least bittern. We have one naturalized species: the cattle egret, which is native to Africa. All these species, except for the green heron and cattle egret, are tracked by the CNDDB. Be sure to fill out an Online Field Survey Form if you come across a nest site!

Top Left: One of the many trees used by the Fairfield rookery. The white birds are the SNEG. For every SNEG in the photo, there is likely a black and white BCNH adult or brown and white BCNH juvenile present but blending in with the tree. Top Right: Closer image of SNEG. Bottom Left: Fledglings under one of the nest trees – 3 SNEG and 1 BCNH. BCNH are known to have a high tolerance for disturbance as is evident in the proximity of the rookery to homes, traffic, and park-goers. Bottom Right: BCNH fledgling on park sidewalk.

Please join our next Conservation Lecture Series talk that focuses on how extreme climatic events have recently impacted marine ecosystems around the world, including foundation species such as kelps. We quantify the rapid climate-driven catastrophic shift in 2014 from a previously robust kelp forest to unproductive urchin barrens in northern California. Bull kelp canopy was reduced by 93% along >350 km of coastline. Twenty years of kelp ecosystem surveys reveal the timing and magnitude of events, including mass mortalities of sea stars (2013-) and red abalone (2017-), extent of nearshore ocean warming (2014-2017), and the sea urchin population explosion (2015-). These stressors led to the unprecedented and long-lasting decline of the kelp forest and the ecosystem services is supports such as the red abalone and sea urchin fisheries.

Date: Thursday, July 18, 1:00 - 2:30 p.m.
Register to view online.

Questions? Contact: Whitney.Albright@wildlife.ca.gov

CNDDB staff had the opportunity to join Ben Ewing, the Alpine, Amador, Calaveras, and Lake County District Fisheries Biologist, to conduct a backpack electrofishing survey on a northern tributary to Indian Valley Reservoir. The electrofishing gear would stun the fish long enough for a second person to scoop it up with a dipnet and place it in a bucket of water. The collected fish would then later be identified and measured. This area had never been sampled by CDFW, so our findings were useful in setting a baseline for the stream.

We collected and released largemouth bass, California roach, speckled dace, and incidentally detected a foothill yellow-legged frog. A CNDDB query showed that the last time someone searched and found foothill yellow-legged frog was in 1994. Being able to update this 25-year old occurrence was an exciting bonus.

Thank you, Ben, for sharing your knowledge and expertise with us!