Eggs |
Welcome to our new webpage on egg identification! Many of you have wondered how to identify reptile and amphibian eggs, so we decided to put together a preliminary guide. We expect this guide to evolve as we obtain new information, so please share your knowledge, especially if it relates to Nova Scotia! If you have any doubt whatsoever about your egg identification, please do not enter the information as an atlas record. If you would like more help with egg identification, feel free to send us a picture. Pictures taken with the subject next to a ruler and with information on the number of eggs, habitat type, and time of year are the most useful.
Remember
that eggs are future adults: damaging or destroying eggs, however inadvertent,
reduces a population's ability to survive and can lead to population declines.
Please allow herp eggs to develop in peace. In particular, remember that
turtles are very vulnerable to predators and avoid disturbing nesting turtles.
Never dig up developing eggs. Instead, examine the shells once the eggs
are hatched.
There
are only two snake species that lay eggs on Nova Scotia, the
Smooth Green Snake
and the
Ringneck Snake.
The way to tell the eggs of the two apart is to look at their colour and
shape.
Smooth Green Snake eggs are white and cylindrical whereas Ringneck Snake eggs are yellowish
and comma-shaped or straight with one fat end.
Otherwise, clutch size and egg size are similar in both species.
Smooth
Green Snakes lay 3-8 eggs that range in size from 19-37mm and Ringneck Snakes lay 1-8 eggs that range in size from 21-36mm. Both species
lay their eggs under rocks or rotting wood, seeking the sauna-like conditions
created by a damp substrate and a rock/wood surface heated by the sun. Both
species sometimes lay their eggs in communal nests, so if you find dozens
of eggs together, you've found the reproductive output of several females.
Ringneck Snake eggs hatch in 2 months and the hatchlings mature in 2-3 years.
Smooth Green Snake eggs hatch in 1-3 weeks and the hatchlings can mature in
their second year.
Ringneck Snake eggs Smooth Green Snake eggs
Photo: NS Museum of Natural History. Photo from Nova Scotia.
Photo: NS Museum of Natural History. Photo from Nova Scotia.
All turtles lay their eggs in sand, gravel or cobble areas, including exposed river bars, beaches, and road, railroad or bridge embankments. Often people find the hatched, dried and distorted eggshell fragments, and in that case it is difficult or impossible to tell whether the original shape was spherical (completetly round like a ping pong ball) or ellipsoid (elongated like a typical bird's egg but equally rounded at both ends).
Snapping Turtle
Snapping Turtles lay 20-40 eggs per clutch
from late June to early July. The eggs are spherical and 28.5-35.5mm in
diameter.
Photo: NS Museum of Natural History.
Photo from Nova Scotia.
Wood Turtle
Wood Turtles also lay their eggs in late
June to early July, but there are fewer eggs per clutch (4-12 eggs) and
they are ellipsoid in shape (3-4 cm long). Wood Turtles generally move farther
from the water to lay their eggs than Snapping Turtles.
Blanding's Turtle
Blanding's Turtles lay their eggs slightly
earlier, starting in early June and continuing to early July. Females
lay 10-12 eggs per clutch. The eggs are ellipsoid and somewhat larger in
diameter than Wood Turtle eggs.
Photo: NS Museum of Natural History.
Photo from Nova Scotia.
Painted Turtle
Painted Turtles lay their eggs at the same
time as Blanding's turtles (early June-early July), but lay 5-10 eggs
per clutch. The eggs are ellipsoid and are about 3.3 cm long and 2.3 cm wide.
Sometimes amphibians eggs are easier to find than the adults, so it can be a great way to complete target squares without spending a lot of time looking. This is especially true for species such as Wood Frogs and Yellow-spotted Salamanders, whose eggs are readily found in early spring.
Many amphibian eggs can be identified by the time of year they appear, whether they are laid in masses, the number of eggs per mass, and the shape of the egg mass. Keep these key features in mind as you embark on your egg identification odyssey.
Yellow-spotted salamanders
Time:
Early spring (April mid-May)
Description:
Globular or sausage-shaped egg masses.
When first laid, egg masses are
very compact (6-6.5 cm in diameter), but after they absorb water, they swell
to over 10 cm in diameter.
Each egg is surrounded
by a conspicuous clear or slightly cloudy gelatinous envelope forming an
egg capsule. The vitelline membrane is about the width of an ovum away
from the ovum. Interestingly, a green alga often grows within each egg capsule
giving the egg mass a greenish colour. By supplying oxygen, the alga promotes
larger embryos, which hatch earlier and are more likely to survive. Wood
Frog and Yellow-spotted Salamander egg masses can be confused. Note that
Wood Frogs deposit many more eggs in each egg mass than Yellow-spotted Salamanders.
Clutch Size:
Each female lays 2-4 egg masses, which each contain 100-400 eggs. If
disturbed, females can lay smaller egg masses (15-20 eggs).
Egg Habitat:
Females lay eggs in woodland ponds, vegetated coves of lakes, quiet
vegetated portions of streams, and roadside ditches. These water bodies may
be ephemeral. Egg masses have never
been observed from lakes with large predaceous fish. Egg masses are attached to submerged
vegetation or rest on the bottom. Several females may use the same spot
to lay their eggs, so you may see several masses together (picture at
bottom or right).
Time to hatch:
1-2 months depending on water temperture.
Photos: Jim
Wolford (left or top) and Dave Harris (right or bottom). Photos from Nova
Scotia.
Blue-spotted salamanders
Time:
Early spring (April mid-May)
Description:
Females lay their eggs either individually or in little groups
of 2-30 eggs. The egg masses tend to be rather loose unlike the firm consistency
of Yellow-spotted salamander egg masses. The jelly around the eggs is
quite clear and the vitelline membrane around the ovum is very near to
the ovum.
Clutch Size:
Each female lays approximately 70-550 eggs per year.
Egg Habitat:
Eggs are laid in shallow woodland ponds and ditches that do not
contain large, predaceous fish. Eggs are placed on the bottom or at the base of vegetation
or rocks.
Time to hatch:
3-4 weeks.
Blue-spotted
Salamander egg masses to the left and right of the larger, central Yellow-spotted
Salamander eggs
(Photo:
Massachussetts Vernal Pool Association
)
Eastern Redback Salamander
Time:
Summer (June and July)
Description:
These salamanders are the only ones in Nova Scotia that lay terrestrial
eggs. They are also one of the few herps to provide parental care to their
young. Females guard their eggs for 6-8 weeks and remain with the hatchlings
for 1-3 weeks. Females aggressively drive off other female Red-backed
Salamanders by biting, snapping and lunging. If a brooding female is unable
to drive off the intruder, the intruder may eat the eggs. When females
are removed from the nest, egg survivorship is very low. Each egg is 3-4mm in
diameter and is surrounded by two jelly envelopes resulting in a total
diameter of 3.5-5mm.
Clutch Size:
Females lay 4-17 eggs in small clusters.
Egg Habitat:
The females lay their eggs in cavities inside moist rotting wood
or under thick mats of moss.
Time to hatch:
Eggs develop directly (no larval stage) and the juveniles,
which look like miniature adults, hatch after 1-2 months in August or September.
Photo: Jim
Wolford. Photo from Nova Scotia.
Four-toed Salamander
Time:
Early spring (April to mid-May)
Description:
Female Four-toed salamanders lay their eggs in small clusters in
sphagnum moss slightly above water, and remain with the eggs until they hatch. If nesting habitat
is scarce, several females may lay their eggs together in a communal
nest with one or two females in attendance. Eggs are 2.5-3mm in diameter and
are covered by two jelly envelopes.
Clutch Size:
Females lay approximately 20-40 eggs per year.
Egg Habitat:
Eggs are laid within sphagnum moss hummocks a few centimeters over
water so that the larvae can drop into water once they hatch.
Time to hatch:
Six to eight weeks.
Photo: Nova
Scotia Museum of Natural History. Photo from Nova Scotia.
Red-spotted Newts
Time:
Spring (April to June)
Description:
These eggs are very difficult to find because the females lay them
singly. Females only lay a few eggs per day, so it takes her several weeks
to lay the entire clutch. Eggs are 1.5mm in diameter and are surrounded by a
three jelly envelopes. Vegetation often adheres to the sticky outer envelope.
Clutch Size:
Females can lay approximately 80-450 eggs per year.
Egg Habitat:
Females attach their eggs to the bottom or to submerged vegetation,
rocks, and sticks.
Time to hatch:
An aquatic larval newt hatches from the egg in 1-2 months.
We are on the lookout for pictures of Red-spotted Newt eggs.
If you have any, please let us know!
Eastern American Toad
Time:
Late spring (May)
Description:
Toads are the only Nova Scotia amphibian to lay their eggs in strings.
Females lay one string from each oviduct producing a double strand of
eggs. Each strand is only a couple of eggs wide, but it is several meters
long. Strands often become tangled and covered in silt.
Clutch Size:
Females lay 4,000-8,000 eggs.
Egg Habitat:
Lake and pond shallows. Toads avoid laying eggs in areas where Wood
Frog tadpoles are present.
Time to hatch:
2-8 days.
Photo: Jim
Wolford. Photo from Nova Scotia.
Spring Peepers
Time:
Spring (April-May)
Description:
Like the Red-spotted Newts, female Spring Peepers lay their eggs
singly or just 2 or 3 together. Eggs are very small
(1mm in diameter).
Clutch Size:
Females can lay 400-1,500 eggs per year.
Egg Habitat:
Females deposit their eggs in shallow still water, attached to
the bottom or to submerged vegetation, rocks or sticks.
Time to hatch:
6-12 days.
Spring Peeper
eggs (look closely for the small round eggs). Photo: Jim Wolford. Photo from
Nova Scotia
Wood Frogs
Time:
Early spring (late March to early April)
Description:
Wood Frogs lay egg masses at communal sites. When first laid, egg
masses are very compact, but after they absorb water, they swell to 6 - 10 cm. Communal spawning
is thought to help keep the eggs from freezing because the small black
embryos, which absorb heat, and the thick jelly mass, which acts as an
insulator, can raise the temperature within a large cluster to 6C higher
than the surrounding water. Wood Frog egg masses may also contain green
algae. Individual eggs are 2mm in diameter.
Clutch Size:
Each mass contains 500-1,200 eggs, a much greater number than Yellow-spotted
Salamanders.
Egg Habitat:
Egg masses are laid in any body of water near on in woods.
These water bodies may be
ephemeral.
Females prefer small ponds that
are well shaded by trees. Egg masses are attached to submerged sticks or
vegetation with the top of the egg masses at the surface.
Time to hatch:
15-20 days, depending on the water temperature.
Photo: Jim
Wolford. Photo from Nova Scotia.
Leopard Frogs
Time:
Spring (mid-April to mid-May)
Description:
Leopard frogs lay their eggs in loose, flattened, oval-shaped masses.
Egg masses are 8-13 cm in diameter. Individual eggs are 1-2mm.
Clutch size:
Egg masses contain 2,000-6,000 eggs.
Egg Habitat:
Females lay their eggs in the shallows of ponds, lakes, cattail
marshes or drainage ditches. Eggs are attached to submerged sticks or
vegetation. The egg masses are in shallow water such that the underside of the
egg mass rests at the bottom and topside breaks the surface of the water.
Time to hatch:
13-20 days.
Photo: Nova
Scotia Museum of Natural History. Photo from Nova Scotia.
Pickerel Frogs
Time:
Late spring (May)
Description:
Eggs are greenish or light brown at one end and yellowish or white at the
other end. Eggs are laid in globular masses. Egg masses are 5-10 cm in
diameter and individual eggs are 2 mm
in diameter.
Clutch Size:
Each egg mass contains 800-1,800 eggs.
Egg Habitat:
Females attach the egg masses to submerged sticks or vegetation
and tend to lay their eggs in gently flowing streams and cool shaded woodland
ponds.
Time to hatch:
12-18 days.
Photo: Scott
Egan. Photo from Rhode Island.
Mink Frogs
Time:
Summer (July)
Description:
Females lay globular egg masses that are 7.5 - 15 cm in diameter.
Clutch size:
There are 2,000-4,000 brown-black eggs in each egg mass.
Egg Habitat:
Females lay eggs in vegetated coves of lakes or slow-moving vegetated streams
and attach their egg masses to submerged sticks or vegetation. Egg masses
drop to the bottom after laying and can be quite deep (up to 2m below the surface),
which means that they are seldom
observed. Eggs are generally laid in permanent bodies of water because Mink
Frog tadpoles require a year to develop.
Time to hatch:
No records available.
Photo: Jim Wolford. Photo from Newfoundland.
Green Frogs
Time:
Summer (early June through July)
Description:
Female Green frogs lay their eggs as floating pancake rafts that
stick to vegetation. The rafts are only one or two eggs thick, an adaptation
that exposes all the embryos to warm summer air temperatures and speeds-up
development. Individual eggs are 1-1.5mm in diameter. Egg masses are usually
less than 30 cm in diameter.
Clutch Size:
Each egg mass contains 1,000-4,000 eggs.
Egg Habitat:
Green Frogs lay their eggs close to shore in vegetated areas.
Eggs are generally laid in permanent water bodies because tadpoles take a
couple of years to develop.
Time to hatch:
Embryos develop so quickly that small tadpoles hatch within four
days.
Photo: Jim
Wolford. Photo from Nova Scotia.
Bullfrogs
Time:
Summer (mid-June through July)
Description:
Like Green frogs, Bullfrogs also lay their eggs as floating pancake
rafts but the egg mass can be several layers thick. Egg masses are usually
more than 30 cm in diameter.
Clutch Size:
Egg masses contain 10,000-20,000 eggs, many more than a Green frog
egg mass.
Egg Habitat:
Eggs are laid on the water surface among aquatic vegetation. Eggs
are black and white and measure 1.2-1.8mm in diameter. Capsules around
eggs are not distinguishable. Bullfrog eggs are generally found in deeper
water where lily pads grow. Green Frog eggs are closer to shore.
Eggs are generally laid in permanent
water bodies because tadpoles take a couple of years to develop.
Time to hatch:
4-5 days.
We do not have any photos of Bullfrog eggs. If you have a good picture, we would love to use it!
The information on this web page was taken from:
A Virtual Exhibit on Canada's Biodiversity: Focus on Amphibians
The Canadian Amphibian and Reptile Conservation Network
A guide to frog egg identification and metamorphic timing
Gilhen, J. 1984.
Amphibians and Reptiles of Nova Scotia. The Nova Scotia Museum. Halifax,
NS.
Halliday, T. and K. Adler. 1991. The Encyclopedia
of Reptiles and Amphibians. Facts on File Inc. New York.
Hunter, M.L. Jr., A.J.K. Calhoun, and M. McCollough. 1999.
Maine Amphibians and Reptiles. The University of Maine Press. Maine.
Petranka, J.W. 1998.
Salamanders of the United States and Canada. Smithsonian Institution.
Washington.
Stebbins, R.C. and
N.W. Cohen. 1995. A Natural History of Amphibians. Princeton University
Press. New Jersey.
All photos used with permission.