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Got eggs? This UC Berkeley museum has tens of thousands.

The Museum of Vertebrate Zoology has one of the largest collections of eggs in North America, and it's vital to researchers worldwide.

By Gretchen Kell

Professor Rauri Bowie at the Museum of Vertebrate Zoology looks at a drawer of eggs in the museum's egg collection. There are large eggs in boxes that include ostrich, emu and cassowary eggs. The emu eggs are dark brown, the others are light colored. The ostrich eggs are shiny.
Rauri Bowie, Berkeley professor of integrative biology and a curator at the Museum of Vertebrate Zoology, opens one of the museum's countless cabinets of eggs. This one's contents include a greenish cassowary egg (left) and two dark-colored emu eggs (center and right). Shiny white ostrich eggs lie in the top drawer.

Charlotte Khadra/UC Berkeley
A cassowary egg sits on cotton batting in a box. A professor is holding the box while someone touches the egg's shell with their fingers to feel the shell's texture. The egg is a shade of green that helps to camouflage it.
This cassowary egg from Papua New Guinea was collected in 1934. The cassowary is a flightless bird native to the tropical forests of New Guinea, the Moluccas and northeastern Australia. Its eggs are among the world's largest bird eggs and have a deep green, textured shell that's used as camouflage among dense forest foliage.

Charlotte Khadra/UC Berkeley
A dark-shelled emu egg sits on a bed of cotton in a box at the Museum of Vertebrate Zoology. It's large enough that 12 chicken eggs could fit inside and is a very deep brown. The shell has a hole in it, and the egg was found in Australia.
The eggs of emus — tall, flightless birds native to Australia — are striking in both size and color. They're large enough that 12 chicken eggs could fit inside. Their color ranges from deep green to almost blue-black. Over time, exposure to UV radiation naturally darkens the green hue, gradually turning the shell glossy black.

Rauri Bowie/UC Berkeley
An elephant bird eggs sits on cotton batting in a carboard box in the Museum of Vertebrate Zoology on campus. It is enormous, about 13 inches long and is oblong, with a surface that is a bit craggy and shows partial mineralization.
The largest bird eggs ever laid came from the now-extinct elephant bird. This specimen at the museum shows partial mineralization, a result of its subfossil state after being recovered from a cave in Madagascar.

Marissa Gutierrez/UC Berkeley
Two white Anna's hummingbird eggs rest on cotton in a clear small box in the Museum of Vertebrate Zoology. They resemble jelly beans and are marked with a tag that says they were collected in El Cerrito, California, in June 1954.
The world's smallest bird eggs are from the hummingbird. These white Anna’s hummingbird eggs resemble jelly beans and were collected in El Cerrito, California, in June 1954. Most hummingbirds lay two eggs per clutch.

Rauri Bowie/UC Berkeley
This drawer of eggs in the Museum of Vertebrate Zoology contains boxes of peregrine falcon eggs, which are rust-colored and speckled.
Peregrine falcon eggs are rust-colored and speckled. Here are two sets: The four boxes on the left were collected between 1898 and 1899; the four on the right date from 1939 to 1946. These eggs, along with the broader museum collection, played a pivotal role in revealing how the eggshells of birds of prey thinned because of the pesticide DDT, which was banned in the 1970s. The ban allowed falcons and other birds to return from the brink of extinction.

Charlotte Khadra/UC Berkeley
The body of a passenger pigeon and a passenger pigeon egg in a small box are in the Museum of Vertebrate Zoology. The pigeon is slim with a rusty-colored breast, a dark head and wings and a white underside to its tail feathers. The egg is white and was collected in May 1860.
The oldest egg in the museum's collection is from the now-extinct passenger pigeon, which Bowie said was "once so abundant that it could darken the sky in massive flocks." The egg was collected in May 1860. The death of the last known passenger pigeon, Martha, was in September 1914 at the Cincinnati Zoo.

Rauri Bowie/UC Berkeley
These seabird eggs at the Museum of Vertebrate Zoology are specked and pointy-shaped, making them less likely to roll away from a nest.
Each of these seabird eggs — all from the common murre —  displays a one-of-a-kind blend of color and pattern. Seabirds can lay four eggs per clutch, and the eggs' teardrop (pyriform) shape allows them to roll into a tight circle rather than off narrow cliff ledges. There's a theory that the shape and resulting tight arrangement of the eggs help conserve heat, a crucial adaptation in windy, exposed nesting sites.

Charlotte Khadra/UC Berkeley
A professor at the Museum of Vertebrate Zoology holds a container with one large egg inside, from the kiwi bird. The container is round, and the white oblong eggs sits on some soft material.
A gem of the museum's collection is a kiwi egg. Native to New Zealand, kiwis are about the size of a rooster, yet they lay an enormous egg that can weigh up to 20% of the female’s body mass. In comparison, a human baby typically weighs about 5% of its mother’s body mass. The kiwi egg is about 70% yolk, providing the growing embryo with protein and energy so that when the chick hatches, it's fully feathered and can walk immediately.

Charlotte Khadra/UC Berkeley
Two large eggs in the Museum of Vertebrate Zoology have unique museum catalog numbers written on them in pencil, like all the eggs in the museum.
Each egg set in the museum is assigned a unique museum catalog number. In addition to being recorded on the tag accompanying the set, the number is carefully written in pencil on each individual egg. This ensures that if eggs are temporarily removed for study, they can be accurately returned to their original box.

Marissa Gutierrez/UC Berkeley
A drawerful of boxes of nests at the Museum of Vertebrate Zoology contains the nest of a magpie that was found in 1924 in Gilroy. Its distinct feature is that its made with horsehairs, as horses and donkeys were instrumental at that time on farms.
This is the nest of a yellow-billed magpie — one of only two bird species found exclusively in California. It was collected in Gilroy on May 10, 1924. Lined with horsehair, the nest offers a glimpse into the past, when horses and donkeys roamed the area, playing a key role in local farming.

Kara Manke/UC Berkeley
A soft nest made by a Canada jay sits in a box in a drawer at the Museum of Vertebrate Zoology. It was made from lichen, spiderwebs and feathers.
One of the museum's 1,300 nests is this beautifully crafted Canada jay nest from Moose River, Ontario. It was delicately woven from lichen, plant fibers and spider silk. Soft to the touch and fragile, the nest is lined with feathers that provided insulation for eggs in the cold northern climates that these jays call home. This specimen was collected on April 15, 2004.

Marissa Gutierrez/UC Berkeley

April 11, 2025

It’s the season for egg hunts, whether you’ll be searching for the plastic, candy-filled kind or — due to the avian flu outbreak — an affordable dozen at the grocery store.

At UC Berkeley, there are nearly 14,800 sets of bird eggs — 57,883 eggs in all — and 1,300 bird nests at the Museum of Vertebrate Zoology. The museum has one of the largest collections of eggs in North America.

In the drawers of custom-made steel cabinets, the egg specimens are stored in boxes with see-through tops so they can be viewed without handling. The cabinets have airtight rubber seals, since the museum doesn’t use chemicals to deter pests.

These drawers at the Museum of Vertebrate Zoology hold containers of white owl eggs. They are round, and each container is marked with a white tag that says where and when they were collected.
Here’s a selection of owl eggs at the museum. The top drawer holds the small, white eggs of the burrowing owl, while the bottom one contains the larger eggs of the great horned owl.

Marissa Gutierrez/UC Berkeley

The tiniest eggs are from hummingbirds, the biggest from the long-extinct elephant bird. There are oblong, round, speckled, pastel-colored, textured and even pesticide-damaged eggs. The majority are from western North America, the rest from most other continents.

There even are specimens from nearly every extinct North American bird species.

The museum is primarily a research facility for scientists and graduate students. However, it offers many tours, including for local school groups and for classes on the Berkeley campus. In 2024, it hosted 31 tours for about 735 visitors.

A tiny Anna's hummingbird nest iis made of lichen and spiderwebs and sits on a sturdy branch. It's a recent addition to the nest collection at the Museum of Vertebrate Zoology.
This Anna’s Hummingbird nest, crafted with lichen and spiderwebs, is one of the most recent additions to the museum. It has a cup-like shape and is supported by a sturdy branch beneath.

Rauri Bowie/UC Berkeley

The eggs and nests are too fragile to be loaned, so researchers and anyone at a distance can view them, along with their data, in the museum’s online records. Here’s a peek at the museum’s oldest egg specimen, a single egg from 1860 from the extinct passenger pigeon.

In 2024, researchers accessed the online egg collection 7,841,030 times, said Rauri Bowie, Berkeley professor of integrative biology and a curator at the museum. He added that in 2024 alone, data from the museum’s bird collection were viewed online 134,145, 380 times.

Professor Rauri Bowie at the Museum of Vertebrate Zoology holds a large carboard box containing the largest egg in the world, from the extinct elephant bird on the island of Madagascar. The egg is oblong and light-colored and could hold 144 chicken eggs.
Museum curator Rauri Bowie holds a box containing an egg from the long-extinct elephant bird. It’s estimated to be between 1,000 and 3,000 years old and is so large it could hold the equivalent of 150 chicken eggs or 12,000 hummingbird eggs.

Charlotte Khadra/UC Berkeley

Today, collecting and possessing wild bird eggs is generally illegal under the Migratory Bird Treaty Act and other laws. The eggs in the museum primarily stem from the 1800s and early 1900s, when egg collecting was popular. Today, new specimens are added occasionally to the collection through salvage, gifts and confiscations by the U.S. Fish and Wildlife Service.

Recently, the museum received and catalogued 83 egg sets and four nests. They were donated by the son of a former Berkeley alumnus who collected eggs as a hobby in the 1930s.

It also accepted a donation of 520 egg sets that the U.S. Fish and Wildlife Service took possession of following the death of another egg collector.

Bowie said the museum is fulfilling the vision of its founding director, Joseph Grinnell, a professor of zoology. It’s doing so by making novel discoveries through the comparison of specimens, including eggs, using time series data and the exceptional field records that Grinnell and his colleagues preserved.

Two boxes of rust-colored, specked falcon eggs at the Museum of Vertebrate Zoology show eggs collected in the late 1800s, plus a cracked egg from the 1960s, when researchers were measuring eggshell thickness to determine the effects of the pesticide DDT.
This drawer’s contents include peregrine falcon eggs collected in 1899 (left) and in 1898 (right), plus a cracked egg from the 1960s, when researchers were measuring eggshell thickness to discover the devastating effects of DDT. The pesticide caused the eggshells to thin and jeopardized the survival of bird populations.

Charlotte Khadra/UC Berkeley

“Eggs are remarkable structures,” said Bowie, “and with each new advancement in technology, we uncover even more about them. They offer a window into the past, allowing us to study the effects of environmental contaminants, like DDT, and climate changes, such as shifts in egg and clutch size.”

The museum’s collections also help scientists learn how plant materials used in nest-making can guide habitat restoration efforts, he added, “helping us uncover the original plant species that once thrived in areas like San Francisco Bay, the Galápagos Islands and beyond.”