Author: Christine Healy

In 2022, Conserve Wildlife Foundation was awarded a grant by the Monmouth County Audubon Society to establish artificial nesting areas for barn owls in field and salt marsh habitats within the county. Most of the barn owl activity recorded in New Jersey occurs in Salem and Cumberland counties, where population density and development are comparatively low. Though barn owls are sighted in Monmouth, there is no evidence of nesting activities at present. By providing boxes for owls in appropriate habitat types, we hope to encourage this to change. Our project proposal had 4 objectives:

1. Select 3 locations suitable for nesting barn owls within Monmouth County.
2. Construct owl boxes.
3. Install boxes within chosen parks.
4. Monitor for occupancy during the nesting season.

Former CWF biologist, Meghan Kolk, worked with the Monmouth County Parks System (MCPS) and the state to isolate promising locations with adequate features (open space for hunting rodents, distance from roads, etc.) to support nesting owls. In 2023, CWF biologist Christine and senior biologists Larissa and Ben took over the management of program deliverables.

Barn owls are the most widespread species of owl; they occur on all continents except Antarctica and span a multitude of habitat types including open fields, shrublands, savannas, and coastal marshes, among others. Given this vast geography, it may be unsurprising that approaches to their conservation, particularly where nest boxes are concerned, are as varied as their landscape. Sorting through design plans or available products can be overwhelming, though most organizations will agree on a few major elements that will increase usage and success.

First, barn owls, at ~16” tall, are relatively large birds. Females lay clutches of 4-6 eggs and the chicks remain in the nest box for ~55 days after hatching. According to the Barn Owl Trust, a satiated owlet’s weight can exceed that of its parents by 100 g by 6 weeks of age. All this to say, barn owl boxes are no small thing… For perspective, transporting three in a Subaru Forester with the seats down was a challenge. The owl’s size also influences the point of entry. A well-constructed box should have an opening that mimics a natural nesting cavity- providing a comfortably tight squeeze for the owl while excluding larger predators. The opening should be positioned high on the box to prevent the owlets from falling out. Painting the exterior white can help ensure appropriate thermal conditions and allows researchers to determine occupancy. Finally, barn owl feathers are adapted to enable near-silent flight which makes them less tolerant of the rain than other birds. The roofs of barn owl boxes should be reinforced with caulk (or hot glue) to provide some level of waterproofing.

Christine and her dad, Jim, assembled three boxes this past fall, as reported in a previous story. They utilized specs provided by the Barn Owl Research Institute, which have been used to good effect in New Jersey for over 40 years and utilize all the features listed above.

On December 7^th, CWF installed the first box in Big Brook Park in Marlboro. As a veteran when it comes to this type of work, Ben instructed the team on the fundamentals of constructing a cantilevered base and ensured the box was nice and stable for future occupants as well as volunteers who will be responsible for replacing the pine mulch substrate each year. Prior to its purchase by the Monmouth County Parks System, Big Brook was a dairy farm and piggery. The back half of the park contains several large tree-lined fields which makes it a great candidate for rodent-loving barn owls.

We returned to Monmouth County on December 20^th to install our remaining two boxes, this time in salt marsh environments. Bayshore Waterfront Park, part of the County Parks system was chosen as the first site. Located in Port Monmouth on Sandy Hook Bay, this spot was the most residential area chosen for this project. The most promising habitat occurred on associated land outside the main park so, in the event the box becomes occupied, the owls should remain undisturbed. Access required bushwhacking through tall phragmites and crossing multiple tidal ditches, which should help further discourage visitation. The final box was placed at Conaskonk Point in Union Beach- an area of state land managed by the Cheesequake Park rangers. Each installation took about 3 hours, so we were fighting for daylight during this last effort. The consistency of the sediment made it difficult to reach the recommended depth for the support beams but with a little ingenuity and upcycling of marsh debris, we got the job done before we lost the sun.

To reduce the amount of materials we needed to lug through the marshes, we chose to complete much of the post assembly near the truck, which attracted the attention of several landowners with properties bordering the habitat. We were very pleased that they all expressed excitement at the prospect of new avian neighbors!

Barn owl courtship and egg laying typically begins in March. During this time, they are very sensitive to disturbance and the risk of nest abandonment is high. We will keep our distance from the boxes until mid-May, at which point we would not expect the parents to leave their owlets. We can easily check for signs of occupancy by looking for scratches in the paint surrounding the entry hole. If the boxes are occupied, we will investigate the interior using a camera on a telescoping rod to minimize stress. We will return once more to band the chicks prior to fledging. If the boxes are unoccupied, we will visit again in the fall to ensure we are aware of any late-season activity. Stay tuned for further updates on this exciting project!

We are very grateful to the Monmouth County Parks staff, particularly park naturalist, Paul Mandala and environmental specialist, Rob Fanning for their assistance with site selection, permitting, and the installations at Big Brook and Bayshore Waterfront parks. We were also fortunate to have the help of Cheesequake superintendent, Jon Luk, during our efforts at Conaskonk Point, who also facilitated permissions with the state.

Special thanks to the Monmouth County Audubon Society for funding this project and to CWF biologist, Emmy Casper, who also helped with the marsh installs.  

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.

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.

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!  

This post is the second in our “super salamander (and frog)” series in which we’re exploring some of the unique adaptations exhibited by local amphibians that would seem more appropriate within the confines of a comic book than out and about in our Garden State landscape. Today’s focal species is the spotted salamander (Ambystoma maculatum), our benevolent Poison Ivy. Full disclosure, this topic has nothing to do with plant, though salamanders themselves are not sensitive to the compounds that make humans itchy and have been known to use “leaves of three” as sources of shelter.

For those of you who may be unfamiliar with the DC Comic Universe, Poison Ivy is a villain who often opposes Batman (and occasionally Superman) during her crusade to protect plants and rid the world of environmental destruction. Though her goals may seem in line with ours here at CWF, her methodology differs dramatically and she is often defined as an eco-terrorist. A former botanist, Poison Ivy, AKA Pamela Isley, was poisoned by her professor. Though she survived the experience, the toxins drove her insane and transformed her into a human-plant hybrid. And that is where our connection lies…

If you’ve ever seen an egg mass deposited by a spotted salamander, you may have noticed that the casing often appears green. This is caused by an association with a very particular kind of green algae called Oophilia amblystomatis. The connection between salamanders and algae has been recognized for > 130 years. For most of that time, it was thought that the algae just occurred within the egg. This is a sensible mutualism- it is auspicious to both species involved. Spotted salamander eggs develop in vernal pools. These temporary wetlands may have relatively low concentrations of dissolved oxygen, so the introduction of algae, which can create oxygen through photosynthesis, into eggs can certainly benefit growing larvae. Under experimental conditions where salamander eggs containing algae were cut off from sunlight, growth and development was delayed and resulting individuals were smaller than those exposed to natural circumstances. On the other side, larvae produce CO₂ and nitrogenous wastes, which can be used to the advantage of the algae. Studies have shown that Oophilia are most successful in water that has been exposed to spotted salamander eggs, even if they are not within the eggs themselves. Case closed, right?

Wrong. In 2011, a team of researchers at Dalhousie University in Halifax, Nova Scotia, discovered that the relationship between these two organisms is, literally, skin deep… The algae don’t just infiltrate the salamander’s egg masses. They are also found within the salamander’s tissue cells. This type of connection is called an endosymbiosis- one cell living inside another cell. Coral reefs and their associated algae are the poster children for this phenomenon, but it is not uncommon among invertebrates. Vertebrates, however, tend to have much more active immune systems that are programed to recognize a cell growing within another cell as a health threat. We can be grateful for that, as dangerous pathogens (e.g., malaria), can spread this way. In the case of salamanders and algae, the above-mentioned team discovered that the amphibians were actively suppressing their immune systems to allow for the success of the algae, which indicates that they must continue to benefit from this association. The algae show signs of stress when encapsulated within the body of salamanders; sunlight becomes harder to access, so rather than creating energy through photosynthesis, they switch to the process of fermentation.

The endosymbiotic mutualism between spotted salamanders and green algae is totally unique among vertebrates. No other amphibians, reptiles, mammals, birds, or bony fish are known to support a similar relationship. Research on the mechanisms and the meanings of this “partnership” are ongoing, but scientists are hopeful that the discovery could yield novel techniques for medical advancement.

While spotted salamanders are certainly not hybridizing with their algal associates, in a way, they walk the animal-plant boundary as they incorporate both types of cells within one compact package, therefore making them the amphibious analogs of DC’s Poison Ivy.

Our final installment will shift the focus to frogs and, in particular, one that doesn’t mind the late winter chill…

by Christine Healy, Wildlife Biologist

I felt confident, after the mild conditions that we experienced in January and much of February, that March would skip the “lion” phase of the well-known adage and come in and out like a lamb. I was clearly incorrect…

In anticipation of the amphibian migration, I thought it would be fun to write about some of the most unique adaptations displayed by three early-breeding vernal pool obligates that we target during our Crossing program. These species require access to temporary wetlands in order to complete their life cycles and are thus at greater risk of motor vehicle collisions than other amphibians that don’t rely on these resources. As I started drafting this, I kept thinking about parallels between the behaviors that I chose for each species and superheroes/villains whose background and abilities relate. And so, I’m kicking off this series with our very own Wonder Woman, the Jefferson Salamander.

Continue reading “New Jersey’s Amphibious Amazons”