Conserve Wildlife Blog

Posts Tagged ‘winter’

Frozen Frogs

Friday, March 24th, 2023

We’ve made it to the final “super species” in our “superhero” series though, like in the last post, we’re spotlighting an adaptation that aligns with one of the more notorious residents of Gotham City. Our local frog has all the chill, while this DC villain needs to chill… quite literally, as his sub-zero body temperature must be maintained to ensure his survival. Cryogenics expert, Dr. Victor Fries- better known as Mr. Freeze, had admirable intentions when he began his experimentation with ice. Unfortunately for him, accidental exposure to chemicals altered his physiology, necessitating the use of an air-conditioned suit and spurring a life of crime motivated by tragic desperation. The compound responsible for his transformation is thought by some to be glycerol, which also happens to be the key to the winter survival strategy of our favorite early breeding anuran- the wood frog (Lithobates sylvaticus).

Animals living in temperate climates must find ways to cope with the cold temperatures and reduction of food resources, characteristic of the winter season. Some species deal with winter by not dealing with winter… instead they migrate to milder conditions farther south. This is a path commonly taken by birds. Other animals have adapted to have a large body mass. This reduces their surface area and enables them to hold onto heat more efficiently. As a former moose biologist, I’m happy to give them a quick nod here. Many strategies exist across the natural world to increase the odds of persistence, but we’re here to talk about amphibians and, it’ll probably come as no surprise to you that they aren’t employing either of the aforementioned tactics.

Wood frogs are a vernal pool obligate species; they must have access to these temporary wetlands in order to breed and complete their lifecycle, but they don’t live in them all the time. Therefore, we do refer to them as migratory, but they only cover about ¼ to ½ mile during this annual pilgrimage, so temperature differences are negligible. Most frogs and salamanders in New Jersey endure the colder months by entering brumation- the “cold blooded” equivalent of hibernation. In this state, animals can drop their body temperature and metabolism to conserve energy. Some species burrow and use the ground as insulation. Others brumate in streams and ponds since water cools at a slower rate than air. Wood frogs cover themselves in leaf litter (for camouflage) and spend the winter comfortably as frog-cicles. That’s right- they essentially freeze solid and thaw once air temperatures become favorable again.

Under normal conditions, when a cell freezes, ice crystals form internally. These solids can then expand, which damages organelles and ultimately ruptures cell membranes. This leads to cell death. Compounded by damage incurred in blood vessels and dehydration, this would be a fatal situation for most animals. Wood frogs have found a hack to get around these devastating consequences.

A recently thawed wood frog huddled beneath a leaf. Photo credit: Nikki Griffiths.

As temperatures drop, wood frogs continue to produce urine but cease voiding it. Instead, the urine is concentrated into urea, which floods the frog’s bloodstream.  The liver also goes into overdrive, manufacturing vast quantities of glucose, which causes their blood sugar to skyrocket as high as 100x normal levels (a better understanding of how this frog can avoid negative health effects under such conditions could certainly contribute to diabetes research in humans). The urea and glucose create a mixture that acts almost like antifreeze. Once ice crystals begin to form around the blood cells and internal organs, this homemade antifreeze infiltrates, allowing  for the retention of water and protecting the frog’s cells from desiccation and explosion. They can maintain this state for up to 8 months.

This brumation strategy earns wood frogs the “northernmost amphibian in the western hemisphere” superlative as they can be found up past Gates of the Arctic National Park in Alaska.

The 2023 Amphibian season has begun! Drive carefully one upcoming rainy nights. Photo credit: Nikki Griffiths.

That’s a wrap on Mr. Freeze and our Super Species! The Amphibian Crossing is now in full swing. If you are going to be driving after sunset along roads that border ponds in the upcoming rains, watch out for migrating frogs and salamanders. Collisions with motor vehicles can decimate local populations rapidly so please slowdown!  

Winter Bird Watching in New Jersey

Tuesday, January 31st, 2023

by Sherry Tirgrath, Wildlife Biologist

While many residents of New Jersey prefer to spend winter days indoors and away from the cold, there are those dedicated birdwatchers that view the wintertime as an opportunity to get outside and observe species they normally wouldn’t see during the rest of the year. New Jersey hosts a variety of migratory birds, some escaping the freezing temperatures of their Arctic breeding grounds during the harsh northern winters. There are many species that both breed and winter in the Garden State and are easier to locate and observe while trees are bare.  Located on the Atlantic Flyway, New Jersey is also a prime spot for coastal bird watching during the fall and spring migration, with Cape May being one of the most active bird watching hotspots in the country.

A black-capped chickadee on a snowy day. Photo by Blaine Rothauser.
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Photos from the Field: Raising up hope in 2021

Thursday, January 7th, 2021

Eagle Scout candidate Kyle Agudo and Boy Scout Troop 61 give ospreys a boost in the new year

Ben Wurst, Habitat Program Manager

Troop 61 lift an osprey nest platform into place on the coastal saltmarsh. photo by Kathy Agudo.

Humans have played a key role in the recovery and stability of nesting ospreys throughout New Jersey and beyond. Today around 75% of the population, close to 500 pairs, rely on nest platforms designed specifically for them. They provide a stable nest platform, adequate perches, and protection from potential ground predators, aka raccoons. Many platforms are located in very close proximity to people, which make for excellent viewing and educational opportunities. Ospreys are a symbol of a healthy coast and resiliency in a dynamic region.

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#Thankful

Monday, November 30th, 2020

‘Tis the season for osprey nest platform repairs — and being thankful for the volunteers who make it happen!

by Ben Wurst, Habitat Program Manager

AmeriCorps Watershed Ambassadors clean out nesting material from a 20-30 year old nest platform.

After migratory birds depart, leaves fall and northwest winds prevail, a small group of dedicated volunteers descend on our coastal saltmarshes. They’re there to maintain osprey nest platforms. Around 75% of our nesting ospreys rely on these wooden structures to reproduce. They were used to help jumpstart the early recovery efforts of ospreys in coastal New Jersey, where much of their native habitat was lost to development in the 1950-60s. Today many of these platforms are reaching their life span or are very close.

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Piping Plovers and Researchers Return to The Bahamas

Wednesday, December 10th, 2014
PROTECTING PIPING PLOVER HABITAT CRITICAL PART OF CONSERVE WILDLIFE FOUNDATION’S WORK

By: Todd Pover, Beach Nesting Bird Project Manager and Stephanie Egger, Wildlife Biologist

We talk quite a bit about “site fidelity” in connection with our beach nesting bird project. And for good reason, whether it be on the breeding or wintering grounds, these birds, like most wildlife, are strongly connected to specific places and types of habitats. Not just in the general sense; many piping plovers return to the same precise site year after year.

Aerial view of one of several hundred Bahamas islands and cays, with tidal flats, highly suitable piping plover habitat, visible stretching around the island.

Aerial view of one of several hundred Bahamas islands and cays, with tidal flats, highly suitable piping plover habitat, visible stretching around the island.

 

We were reminded of this the last several days as we made our way around Abaco, The Bahamas, in search of wintering piping plovers. Having made a number of trips to Abaco since 2011, we have started to narrow down where it is likely we will be able to find them: the Green Turtle Cay Gillam Bay flat at low tide or the adjacent upper beach hummocks at high tide, Casuarina Point to forage at low tide, a number of the main island’s southern oceanfront beaches for roosting, to name a few. We are still finding new sites, not previously surveyed or documented, but we now have a much better idea of what to look for and on what tide or wind condition.

 

The catch is, this only works if the habitat remains intact and suitable. Back in New Jersey, we know this well, as many of the formerly suitable sites for beach nesting birds are lost forever to development or are highly disturbed by recreational activities so the likelihood of reproductive success is low even if they do choose to nest at those locations. Sadly, our breeding pairs of piping plover are relegated to a limited number of suitable sites, which is not a good recipe for recovery of this endangered shorebird.

 

With its hundreds of islands and cays, many undeveloped or lightly settled, we may be inclined to think this is less of an issue on the wintering grounds in the Bahamas. And relatively speaking, this might be true to some extent, but it would be unwise to believe this will always be the case. Economic forces are a driving factor there, as in anywhere in the world, so the lure of development and commercial use of resources is strong in the Bahamas as well.

Black Flag "K2", a Canadian breeder and one of six color marked piping plovers observed on wintering grounds on Abaco, The Bahamas, this past week by CWFNJ's Todd Pover and Stephanie Egger.

Black Flag “K2”, a Canadian breeder and one of six color marked piping plovers observed on wintering grounds on Abaco, The Bahamas, this past week by CWFNJ’s Todd Pover and Stephanie Egger.

 

Fortunately, there is also a strong incentive to protect shorebirds in the Bahamas. The tidal flats and shallow water habitats that shorebirds use are also important for bonefish, conch, and other fisheries that are important to the local economy and provide jobs. Furthermore, birding and wildlife-based activities are increasing an important part of the tourist sector. However, In order to sustain those activities and opportunities, ecosystems must remain intact and pristine.

 

A number of organizations, local and from abroad, are diligently working to designate more protected areas in the Bahamas. One of the top priorities now, an effort being led by the Bahamas National Trust and National Audubon Society, is to protect the vast flats area in the Joulter Cays, Andros, which are especially important for shorebirds such as the piping plover. On Abaco, where we have been focusing our piping plover work, Friends of the Environment  is strongly advocating for protection of East Abaco Creeks, Cross Harbour, and more recently The Marls.

 

During a survey this past week on Man-O-War, one of Abaco’s offshore cays, we were able to locate a banded piping plover that had originally been marked on its breeding grounds in Canada. In discussing the bird with a local resident who had first spotted it, she was surprised that the bird was remaining in the same spot ever since she saw it two months ago. This was site fidelity illustrated in its truest sense, and in the same vein, the researchers in Canada are already anticipating it will return to the same site to nest next spring. From what we know about piping plovers that is highly likely…as long as we remain committed to protecting the habitat they use.