Good Mamas

Motherhood: All love begins and ends there.

~Robert Browning

It has been a good few months for new mothers at work with several new babies among the staff. So, it seems only appropriate that I share a couple of extraordinary mothers from the Garden’s animal kingdom as well. First, an update on the amazing green lynx spider that I wrote about last time. You may recall she had been sitting with her egg case for a couple of months in the top of some rattlesnake master seed heads in our Piedmont Habitat. Her spiderlings emerged around October 20 after having their egg sac already guarded for about a month by their attentive mom.

Green Lynx spider with yellow jacket

Green lynx spider with a meal of yellow jacket last week (click photos to enlarge)

I have been keeping an eye on her off and on since the eggs hatched and am amazed at her site fidelity, even after most of her offspring had seemingly dispersed. Last week she caught a yellow jacket on one of the warm days when flying insects were out and about. This is the first prey I have seen her capture in all this time, although I heard from some other staff that she had caught a couple of other insects during her ordeal.

Green lynx and young on Dec 1

She is still at it on on December 1…amazing!

I made a special visit to see her last Friday, on December 1, to confirm that she had made it into another month. She is still at it and to my surprise, when I checked my photos, I saw one of her offspring sitting next to her on the egg sac (zoom in on the photo above). It looks like it has molted at least once since I photographed the group in October because the shape and color pattern now more closely resembles the adult female. I plan to keep tabs on this dedicated mom, but I don’t expect her to last much longer, with another wave of freezing temperatures headed our way later this week. She has been guarding this egg sac since late September, a truly amazing feat of motherhood.

Salamander pool in winter NCBG

The salamander pool was high and dry last week

While looking for some trees to use in an upcoming activity last week, I decided to check out the salamander pool in the woods near my office. When I started work last winter its water surface was probably 5o feet across and was a hotbed of activity of animal life, shifting from spotted salamanders and upland chorus frogs in winter to American toads and dragonflies as the seasons progressed. With the lack of rainfall this fall, it was no surprise to see it totally dry last week. This is typical for many vernal pools, and is one reason they are such hot spots for breeding amphibians (due to the lack of fish). I gently lifted a few of the smaller logs lying in what had been the water-filled area this summer, hoping to find some salamanders.

Marbled salamander eggs

Marbled salamander eggs under a log

After turning a few, I found part of what I was looking for – an egg mass of a marbled salamander, but minus the attending adult female. Females typically lay their eggs in September and October in these parts, usually under a log near the edge of a low-lying area that fills with water in the winter and spring. She stays with her eggs until rains begin to fill the pool and cover them (usually late October to December) and then she heads back to her woodland home nearby, leaving the eggs to hatch with hours or days of being inundated. If the rains don’t come, she may head back to the woods before they hatch. I wrote about this interesting species in a post a couple of years ago when we found a very late clutch of eggs (in March) that was finally about to be covered by water. I think the thing that surprised me the most that day was how quickly one of the eggs hatched after I placed it in a small container of water. It hatched within just a few minutes! As reported in my bible of salamander biology (Salamanders of the United States and Canada by James W. Petranka), this is  caused by the release of digestive enzymes (from hatching glands on the snout) that dissolve the egg capsule and allow the embryo to escape.

marbled salamander guarding her eggs 1

An adult female marbled salamander guarding her eggs under a different log

Turning over a nearby log, i found a large female marbled salamander curled up around her egg mass. Studies have shown that egg clutches where the female remains with them until they are covered by water have a higher offspring survival, perhaps because she helps protect them from predation or getting too dry. I carefully laid the log back in place, and wished her well and for rains to soon fill this pool. Another case of a dedicated mother.

newt under log in dry vernal pool

Red-spotted newt under another log

Lastly, on a non-motherly note…the last log I looked under had a somewhat crumpled-looking red-spotted newt laying under it. At first, I thought it was dead, but looking a bit closer, its eyes were open, so I presume it is just lying in a protected spot, waiting for the waters to rise. Let the rains begin…

Pool Patrol

In a recent post, I mentioned that I sampled the woodland pool near the house earlier in the week. The Marbled Salamander larvae have grown considerably since my last visit. Almost every dip of the net brought up one or more of the large, squirming pool predators. When first caught, they were very dark, which is typical of these larvae. But, after being in a bucket overnight, the few I brought to the house turned a much lighter color than normal. I placed them in my small photo tank for a few shots the next morning before taking them back to the pool to set them free.

Marbled Salamander larva

Marbled Salamander larva (click photos to enlarge)

Marbled Salamander larvae are easily distinguished by being the largest salamander larvae in area woodland pools this time of year. This is because, unlike the rest of our pool-dwelling species, they hatch in the fall, rather than the spring. The row of light spots along their sides is another diagnostic feature. The ones I caught this week were all large, between 2 and 3 inches in length. In this area, they usually transform and leave the pools in April or May, so these guys are just about ready to become full-time land-dwellers.

Spotted Salamander larva just after hatching

Spotted Salamander larva just after hatching

When they hatch, Marbled larvae feed on zooplankton and small macroinvertebrates. By the time spring arrives, they are large enough to gulp down much larger prey, including the hatching larvae of a common pool neighbor, the Spotted Salamander. The photo above shows a newly hatched Spotted larva caught in the pool this week. It is less than an inch long and still has the balancers, the two fleshy appendages under the head that help them maintain an upright position in the water. These are present for only the first week or so after hatching. Look closely at the image and you can see one pointing downward between the eye and the gill of the larva.

Marbled Salamander larva 1

Marbled Salamander larva

With the number of Spotted egg masses that are just now hatching, there is a buffet of small prey available to the Marbled Salamander larvae. They patrol the pool and use a lunge and gulp feeding strategy to capture a variety of other organisms as well, including small tadpoles, aquatic insects, and even terrestrial insects that fall into the pool. If food is scarce they are also known to nibble on their cousins, so it is not uncommon to see Marbled larvae missing portions of their tail or limbs.

Marbled Salamander larva head close up

Close up of head showing external gills

I plan to visit the pool again over the next few weeks and look for transforming juveniles around the edges. They will lose the bushy external gills and crawl out of the water to begin a terrestrial life, returning to this, or another low-lying spot, only to mate and lay eggs in the fall. Marbled Salamanders are among the many interesting and beautiful creatures that require these fish-less woodland pools to survive. But I worry about the future of many of these pools. I worry that fewer and fewer people know about the beauty and wonder that lies just beneath the surface of such shallow water habitats, and see them, instead, as just a mosquito hole or a place to drain and tidy up. It doesn’t take much disturbance to the landscape to alter the hydrology of a wetland area and leave it high and dry, eliminating this critical habitat for so many of our fascinating neighbors. If you, or someone you know, has such a pool on your property, I encourage you to sit by it, dip a net in it, get to know it and the inhabitants, and protect it. Our world will be a better place if you do.

Marbled Salamander eggs

Marbled Salamander eggs

Marbled Salamander eggs under log

Two friends from the Museum, Megan and Melissa, invited me to tag along with them yesterday, as they did some fieldwork for a future workshop. Megan made a great find as she and Melissa were turning over logs at the edge of a vernal pool, looking for salamanders – some viable Marbled Salamander eggs. It seemed really late to us for this species to still have viable eggs (when she looked closely, she could see the well-developed embryo moving inside the eggs) so she grabbed a couple to photograph.

Marbled Salamanders have an unusual reproductive strategy compared to many other species in that the eggs are laid in the fall (usually October and November in this area). The female often scrapes out a little area near or at the edge of a vernal pool.  Vernal pools are fascinating and important habitats that may be dry much of the year and then fill with autumn and winter rains. The key is they have no fish, which makes them critical habitats for a number of species of amphibians, invertebrates and other animals. She then will stay with the eggs for some time (often a month or more) waiting for the water to rise so the eggs will hatch. If it remains dry for an extended length of time, she may abandon them and return to her underground burrows in the nearby woods until the next breeding season. Studies suggest that egg clutches where the female remains with them until they are covered by water have a higher offspring survival, perhaps because she helps protect them from predation or getting too dry.

Marbled Salamander eggs

Marbled Salamander eggs

The 50 or 60 eggs Megan found were under a log at the edge of a large vernal pool. It was very moist under the log but the standing water was still a few inches away from the eggs. Embryos develop to the hatching stage within a couple of weeks after being laid, but do not hatch until covered by rising water. So these eggs were very well developed. You can see the front legs and feet, the larval gills, some of the diagnostic lateral spots, and the eyes in the waiting “larvae”. My salamander reference (Salamanders of the United States and Canada by James W. Petranka) states, “when covered by water the embryos become oxygen stressed…this triggers the release (from hatching glands on the snout) of digestive enzymes that dissolve the egg capsule and allow the embryo to escape”. Amazing!

Marbled Salamander eggs

A closer look

We put a couple of eggs in some water in a bug box so I could photograph them. Megan called Jeff Beane, a herpetologist at the Museum, and told him about the find. He said he did not recall seeing any viable eggs this late in the spring so he wanted to document the location. We walked down into the woods to show him, photographed the eggs and then walked back to the car. In those 40 minutes or so, the two eggs had hatched. The reference said it usually takes a few hours to a couple of days after flooding for the eggs to hatch. Guess these guys had waited long enough. The last picture is one of a larva from last year that I pulled from another pool. It was much older and larger than the ones from yesterday.

Marbled salamander larva

Large Marbled Salamander larva