Month: March 2022

Notes from the Field: Monitoring Mudpuppies’ Lives Under the Ice

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The Detroit River in the winter can be an inhospitable place. The temperatures dip into the teens, and the wind whips large plumes of snow from the tips of frozen waves. This large and fairly fast-moving river flows south and southwest, connecting Lake St. Clair and Lake Erie. The river plays an important role as a shipping channel for freighters carrying industrial compounds and other materials used for manufacturing. 

Underneath all of this ice and hustle and bustle, one of the river’s most curious and secretive animals is carrying about its business, breathing with large, bushy external gills, foraging along the rocky bottom for food and undergoing mysterious mating behaviors. This animal is known as the northern mudpuppy (necturus maculosus maculosus), and the frozen and harsh conditions of the Detroit River are just what it’s been waiting for all summer long. 

Winter view of the Detroit River taken from Belle Isle Park.

Mudpuppies are amphibians who inhabit lakes, streams and rivers all throughout the U.S. Midwest and into parts of Canada. It is a type of fully-aquatic salamander that utilizes external gills, which are flush with blood and used to extract oxygen from its aquatic environment. Its tail is large and paddle like, and its skin is covered in a thick layer of slime. These salamanders, like all amphibians, have permeable skin and are considered to be a good indicator of environmental quality. This is one of the reasons the Detroit Zoological Society (DZS) began tracking the health and abundance of mudpuppies back in 2009.

In 2016, the Michigan Department of Natural Resources elevated the conservation status of the northern mudpuppy to a species of special concern. Since that time, the project has continued and expanded, focusing primarily on Belle Isle Park in the city of Detroit. The Detroit Zoo utilizes minnow traps to capture the mudpuppies without harming them while still collecting important data. The traps are baited with smelt and catfish bait to lure these aquatic salamanders into the minnow traps. The traps are set on the first day of the survey and pulled in on day two, so that the animals spend the least amount of time possible inside.  If a mudpuppy is found inside, DZS staff proceeds to gather data and observations about the animal, including size, weight and gender. The gills are checked for health and examined for parasites. The digits on all the limbs are checked for malformations, which could indicate the potential presence of pollutants in the river. 

Mudpuppy being weighed and examined before being released back into the Detroit river.

Once these measurements are taken, the animal is tagged with a Passive Integrated Transponder tag, which is injected into the base of the tail. This transponder can be scanned if the animal is captured again. Additionally, it tells DZS researchers useful information that can be used for future data analysis. In addition to these measurements, data is collected on water quality and additional environmental conditions, such as temperature and dissolved oxygen content. 

Based off the data so far, most mudpuppies are caught in late fall or early winter. During this time, male mudpuppies are pursuing females in the quickly cooling shallow water close to the island. Many times, staff has observed male and female mudpuppies in the same trap this time of year, most likely with the female entering the trap first before the eager male mudpuppy follows her inside. Once mudpuppies have successfully bred, the females deposit their eggs in spring, and within a month or two, the eggs hatch into several hundred baby mudpuppies!

All of this drama is taking place out on the frozen Detroit River. With ice floats and enormous boats hovering overhead, these specialized amphibians continue to live and breed intertwined in an urban environmental landscape that still holds many secrets yet to be revealed.

– Mark Vassallo is an amphibian department supervisor for the Detroit Zoological Society.

March of the Penguins: Polar Plunging Into Penguin Welfare

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This month, the Detroit Zoological Society is bringing you not one, but three blog posts centered around our favorite flippered friends — the penguins who live at the Polk Penguin Conservation Center (read the first and second entry). The facility, which had been closed since 2019 due to waterproofing issues, reopened in February, and we can’t wait to share with you all the stories we have been saving over the past two and a half years.

In our final March of the Penguins entry, learn how animal care staff ensured the flock was thriving while its home was being repaired.

It has been a while since the public has been able to visit the penguins who call the Detroit Zoo home. You might have been wondering – what were the penguins doing during that time? In order to answer that question, staff and dedicated volunteers from the Center for Zoo and Aquarium Animal Welfare and Ethics (CZAAWE) spent nearly every day monitoring the penguins for the last two and half years.

Megan Jones, a research associate for CZAAWE, collects data in the Polk Penguin Conservation Center.

While repairs were being made to the Polk Penguin Conservation Center (PPCC), the penguins returned to their previous habitat, the Penguinarium. Animal care staff went above and beyond to make their extended stay in the Penguinarium more comfortable, including bringing snow into the habitat and even letting the penguins walk around Zoo grounds. The penguins’ move provided us with an interesting opportunity to monitor their transition between habitats and compare how they used their previous space compared to their new home in the PPCC.

The PPCC was designed to give the penguins more opportunities to express natural behaviors. It contains a 326,000-gallon pool, which holds 10 times more water than their previous habitat and is equipped with an adjustable wave machine for the penguins to enjoy. Additional improvements were made while the building was closed for repairs, including adding second snow machine within the habitat, more nesting areas and enhanced lighting.

One of the important roles CZAAWE plays at the Detroit Zoo is monitoring how major habitat modifications impact an animal’s welfare. The Association of Zoos and Aquariums defines animal welfare as an animal’s physical, mental and emotional state over a period of time, which is measured on a continuum from good to poor. Since we can’t ask the penguins what they think about all of the new features, we have to rely on decoding their behavior. CZAAWE staff and volunteers have conducted more than 5,000 observations in order to understand how the new habitat impacts the penguins’ welfare. During every observation, CZAAWE staff and volunteers record several indicators of welfare, including the penguins’ behavior, their location within the habitat and the features of the habitat they are using. Our hope was to see the penguins use a variety of different features and locations within the habitat in addition to engaging in the same natural behaviors as their wild counterparts.

Some penguins explore the grounds while the Zoo is closed. Photo credit: Lauren Brown

We found preliminary results varied between each species. For example, the 25-foot-deep pool in the PPCC was successful in promoting swimming in king penguins, who swam more than 10 times more in the PPCC than in their previous habitat. The macaronis, rockhoppers and gentoos relished their new nesting sites, spending more time engaging in nest building behavior than they did in the Penguinarium. The gentoo penguins began to utilize the elevated nesting sites, a feature they did not use in their previous habitat. Additionally, the chinstraps had the opportunity to discover one of their favorite features of the new habitat – the underwater bubbles! Although we saw many positive signs from the penguins in their new home, CZAAWE’s monitoring revealed that the penguins continued to thrive during their stay in the Penguinarium. They maintained their use of the pool and engaged in a healthy variety of behaviors, which is often considered a positive indicator of welfare.

Arthur, a king penguin residing in the PPCC, enjoys his habitat. Photo credit: Megan Jones

Our research also revealed some patterns regarding the location of each species within their new habitat. The PPCC is split into two sides to emulate the natural habitats of all five species that live at the Detroit Zoo. The southern rockhopper and macaroni penguins, typically found on rocky sub-Antarctic islands, are most likely to be found on the South American side of the habitat when you first walk into the building. The king penguins can be found near the snow piles on the Antarctica side of the habitat, while the gentoos tend to use all parts of the habitat. Our newest residents, the chinstrap penguins, are most likely to be found in the water. Most of the species gravitate toward areas of the habitat that are most similar to their natural habitats!With a new habitat comes new opportunities for both penguins and Detroit Zoo guests! What was once a rare opportunity to see king penguins immersed in the water is now a normal sight at the Penguin Center, and the large viewing windows now make it possible to get nose-to-beak with some of your favorite birds. We are thrilled to welcome you back to enjoy some of the positive benefits that major habitat modifications have had on the penguins at the Detroit Zoo.

Tommy, a gentoo penguin, is observed by researchers. Photo credit: Megan Jones

– Megan Jones is a research associate for the Center for Zoo and Aquarium Animal Welfare and Ethics.

March of the Penguins: A Tough Egg to Crack

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This month, the Detroit Zoological Society is bringing you not one, but three blog posts centered around our favorite flippered friends — the penguins who live at the Polk Penguin Conservation Center. (read the first blog post, here) The facility, which had been closed since 2019 due to waterproofing issues, reopened in February, and we can’t wait to share with you all the stories we have been saving over the past two and a half years. 

Next in our March of the Penguins series, learn how animal care staff saved the life of a hatching macaroni penguin.

We’ve all heard stories from friends and family of difficult birthing events, sometimes resulting from a baby that is positioned incorrectly in the birth canal, often called a breech delivery. You may not realize that something similar can happen during the hatching of a bird. 

Fertilized eggs contain all of the nutrients needed to support a chick during development. As the chick grows, an air pocket forms at one end of the egg. For a chick to survive, it must be positioned so that it can push its beak into this air pocket just before it’s time to begin hatching. Some developing chicks are rotated or positioned incorrectly so that they can’t reach this air pocket – this means that the chick can only survive if given assistance. Over the years, bird and veterinary staffs have worked together to assist the hatching of several developing eggs.

Looking inside of a penguin egg.

The bird staff monitors eggs under development very meticulously. They take daily weights to ensure eggs steadily lose weight, a sign that the air pocket, (otherwise known as an air cell) is growing larger.  The staff also shines a special bright light through the eggs, a procedure called candling. Candling allows you to see an outline of the developing chick and air cell. Once incubation nears the end, radiographs can also be taken to visualize the skeleton of the chick and ensure the embryo is positioned normally.

In 2021, the Detroit Zoo had a single fertile macaroni penguin egg. On day 37 of a 37-day incubation period, radiographs were taken to see if the chick was able to hatch normally. The radiographs showed the chick was malpositioned in a way that can be fatal — the chick was rotated, and the beak would not be able to reach the air cell. We could feel the chick moving, and it seemed strong. After discussing our findings, we decided to begin the process of assisting the chick to hatch. 

Dr. Ann Duncan helping the chick hatch.

The shell was cleaned gently, and a Dremel tool was used to make a small opening. A sterile tool was then used to gradually make the opening larger until the position of the chick’s beak could be confirmed.  We then made a very small hole in the membrane overlying the chick’s beak. This allowed the chick to begin breathing air, so that it can stay strong and continue hatching. Chick embryos develop with the yolk sac outside of their abdomen, and as they near hatching, the yolk sac is gradually enveloped inside of the belly to provide nutrients for the first few days. Through the opening in the shell, we could see that the chick needed more time to absorb the yolk sac. We set the chick up in a warm, humid environment, and checked on it frequently. We also began offering one or two drops of water every few hours. 

She has arrived!

The next morning, we were very happy to see that the yolk sac had been mostly absorbed. We removed more of the shell to expose the belly, cleaned the skin over the belly and placed a suture to hold things in place. We then gently coaxed the chick out of the shell. In all, the hatching process took about 24 hours, which mimics the timeline of normal hatching. The macaroni chick is doing well, and is currently learning to swim in the Polk Penguin Conservation Center. She was named Betty and as you can see is full of character. We are very happy to have been given the opportunity to get her started on a long, healthy life.   

Betty in the Polk Penguin Conservation Center.

– Dr. Ann Duncan is the director of animal health for the Detroit Zoological Society.

March of the Penguins: A King-sized Bundle of Joy

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This month, the Detroit Zoological Society is bringing you not one, but three blog posts centered around our favorite flippered friends — the penguins who live at the Polk Penguin Conservation Center. The facility, which had been closed since 2019 due to waterproofing issues, reopened in February, and we can’t wait to share with you all the stories we have been saving over the past two and a half years.

The Detroit Zoo was very eager to welcome a king penguin chick who hatched in 2020. Even though we have raised many penguin chicks throughout the years, we haven’t raised a king penguin chick in 19 years, so this was truly a “king-sized bundle of joy!”

The rearing of this chick is also an interesting story. During courtship, king penguin pairs form a tight bond, which culminates with the laying of a single egg. Unexpectedly, this was not the case for the parents of this chick. Once the egg was laid, the pair was moved into the rookery with the egg. The rookery is an area within the penguin habitat that provides some separation and privacy while the pair incubates their egg and raises their chick. The female was immediately receptive to the male, lifting her brood patch and showing the male their precious egg. The male appeared receptive initially, but rather than soliciting the egg transfer, he quickly became aggressive towards the female.

Normally, the female will transfer the egg to the male shortly after it is laid, usually within 24 hours. Both will share incubation duties, with the male completing the larger share. We decided to give the male a fake egg for a couple of days, while the female incubated the real egg.  After several days, he proved to be a good egg incubator but was still aggressive towards the female. Once the egg was determined to be fertile, we gave it to the male but knew that we had to develop an alternate plan for rearing this chick. 

Fortunately, another pair whose egg was not fertile met the criteria for becoming foster parents. Egg fostering is a technique we have used in the past with other penguin species, either to give another pair the opportunity to rear a chick or when a pair is not able to rear a chick. The foster male (and the biological male) are actually the last of three king chicks to be reared here 19 years ago. Although the foster male had never raised a chick before, the foster female had raised a couple of chicks previously. In fact, she raised the biological “father” 19 years ago, and therefore is the “grandmother” of this chick!  We initially gave the foster pair a fake egg, and about halfway through the incubation period, we transferred the real egg from the biological male to the foster male.

The average incubation period for king penguin eggs is 54 days. On day 54, we noticed an empty eggshell on the ground near the parents – the chick had hatched! Since then, the male chick has fully grown and was given the name Archie. We love seeing this “royal” bird in the habitat and remembering the special foster story that made it possible.

Come visit Archie and watch this fabulous flock waddle, dive, swim and display other natural behaviors in the Polk Penguin Conservation Center.

Bonnie Van Dam is the curator of birds for the Detroit Zoological Society.