Greetings from zip code 99747 in Kaktovik, Alaska!
Polar Bear Cub Development and Welfare: A Team Effort from the Detroit Zoo
What’s more exciting than a polar bear cub? Two polar bear cubs! The birth of any animal here at the Detroit Zoo is exciting, but polar bears offer special cause for celebration. The Detroit Zoo is proudly home to the Arctic Ring of Life – one of North America’s largest state-of-the-art polar bear habitats. These rambunctious new cubs will grow up exploring the more than 4 acres of outdoor and indoor habitats and are the latest polar bears to call the Detroit Zoo home.
Astra and Laerke were born to mom, Suka, and dad, Nuka, on November 17, 2020. Staff from all over the Zoo watched specially equipped cameras in Suka’s maternity den with bated breath, waiting for the arrival of little Astra and Laerke. Once the cubs made their appearance, it was all hands on deck. Even with expert care, polar bear cubs have a high mortality rate in captivity. With this in mind, the question at the forefront of everyone’s mind was a relatively straightforward one – how do we give these cubs the best shot at long, happy and healthy lives?
Newborn polar bears are blind, thinly haired and weigh only around one pound. Despite being born between November and December, mothers and newborn cubs usually remain in the maternal den until late March or even early April. What happens in those five months is largely unknown. There has been very little long-term monitoring on polar bear cubs due to obstacles such as camera placement and staffing availability, which make observing activity in the maternal den challenging. With the combined efforts of team members with diverse skills and backgrounds, the Detroit Zoological Society has undertaken to monitor and report on the growth and development of Astra and Laerke through their first full year of life. With this project, Detroit Zoological Society staff hope not only to ensure that Astra and Laerke thrive, but also to provide a crucial resource for other zoological institutions around the world endeavoring to rear polar bear cubs.
In order to pursue this goal, the Detroit Zoological Society staff needed to come up with a plan that would grow and change alongside Astra and Laerke. Additionally, we needed to be able to monitor the well-being of the cubs from multiple perspectives, both physical and emotional. Phase One of this project has been championed largely by the Arctic Ring of Life staff, mammal curators, veterinarians and the Center for Zoo and Aquarium Animal Welfare and Ethics (CZAAWE). Just a few days after birth, Laerke appeared to need extra support. After careful consideration, we made the difficult decision to remove Laerke from Suka’s care and continue rearing her in the veterinary hospital. With staff never more than a radio call away, Laerke spent her first few months growing and thriving in a behind-the-scenes nursery before transitioning to her own living space at the Arctic Ring of Life. During this time, we were able to weigh Laerke, measure her, and monitor milestones in her growth. It is important to establish normal developmental ranges so that veterinary staff can assess the health and well-being of the animals under their care. Data gathered by tracking Laerke’s growth spurts and noting her key developmental milestones will go a long way towards understanding the needs of baby polar bears. Meanwhile, using cameras in the behind-the-scenes maternal den, we were able to observe Suka and Astra 24-hours a day, 7 days a week. While the presence of cameras in zoological settings is not unusual, prolonged 24/7 monitoring certainly is! Detroit Zoological Society staff came together to share this monumental task for a full 12 weeks. Animal care staff watched more than 2,000 hours of recorded video (120,960 minutes!) and gathered invaluable data on mother-cub denning behavior.
With hundreds of hours of video data, scientists from CZAAWE offered to help with data analysis, freeing up animal care staff to focus on the growing needs of the cubs. Using this valuable dataset, we have been able to answer questions critical to early polar bear development. How frequently does a baby polar bear nurse? When does a baby polar bear leave the nest for the first time? What does maternal behavior look like for a polar bear? With recent transitions to live observations, we have been able to watch as the cubs become increasingly confident and exploratory. We continue to work together to provide peak care and ensure excellent welfare for Astra and Laerke as they approach their eighth month. We look forward to keeping you updated on their progress!
– Dr. Kylen N. Gartland is manager of applied animal welfare science for the Detroit Zoological Society.
The Heat is On
Summer is in full swing, and with it comes higher temperatures. Detroit Zoological Society staff ensure the animals who live at the Detroit Zoo and Belle Isle Nature Center are comfortable, regardless of what the thermometer says.
In some cases, this means giving animals the choice to either remain in their outdoor habitat or venture inside when temperatures soar. Think about how great you feel when you come into an air-conditioned building after spending time outside! But should they choose to remain outdoors, we ensure their habitats always incorporate multiple areas where the animals can find shade. The amount and location of the shaded areas change with the sun’s movement, and that stimulates the animals to move around in order to thermoregulate, just as they would in the wild. For example, you can often find the lions resting in the alcoves in the wall of their habitat, and built-in caves will serve a similar purpose in the soon-to-open Devereaux Tiger Forest. The pool on the polar bears’ “pack ice” side of the Arctic Ring of Life is even chilled!
For many of the animals, such as the eland, deer, ostrich and flamingos, animal care staff set up sprinklers and misters that can be moved around to create cool areas. Staff also make wallows for the rhinos, who cool down by covering themselves in mud. You may even see some animals enjoying “popsicles”, made by freezing pieces of fruit and vegetables or even fish, depending on the species. Keeping the animals both comfortable and stimulated is part of ensuring great welfare.
These practices are meant to not only keep the animals comfortable, but safe as well. Humans can suffer from serious heat-related issues, and the same is true for other animals. My dog really loves to go for long walks; however, during the summer, we make more of an effort to stay off the pavement and asphalt, and to walk in the shade whenever possible. Dogs don’t sweat to cool off like we do; they cool themselves through their foot pads and by panting, and pavement can heat up to 140 degrees when it is only 80 degrees outside. I also make sure to bring plenty of water with me for both of us!
My dog also enjoys going for car rides, but we have to remember that leaving any animal in a car that isn’t running can be very dangerous. Temperatures inside a parked car can rise very quickly, so leaving our animal companions at home in these instances is safer. It is our responsibility to keep the animals in our care safe, healthy and happy, whether they live at the Zoo or in our homes.
– Dr. Stephanie Allard is the director of animal welfare for the Detroit Zoological Society and oversees the Center for Zoo and Aquarium Animal Welfare and Ethics.
Celebrating International Polar Bear Day
Polar bears are iconic animals, known for their incredible ability to survive in one of the harshest environments on Earth. These marine mammals are the most carnivorous member of the bear family, with a diet consisting primarily of seals. They have a thick layer of fat and waterproof fur, providing insulation in the cold Arctic climate in which they live.
Sea ice is imperative for polar bear survival; they spend the majority of their lives on the ice, relying on it to find a mate, build a den and hunt for seals. In the last 30 years, scientists have seen a dramatic shift in ice within the Arctic Ocean. The amount of “old ice” – ice that stays throughout the summer – is significantly smaller than what it was 30 years ago. The seasonal sea ice is forming later in the year – and melting earlier – directly impacting polar bears’ ability to hunt. As a result, many polar bears aren’t able to build up the fat reserves they need for the summer when food sources aren’t plentiful, and they starve to death.
We know the climate is changing. As humans, we are using fossil fuels such as coal and gas to drive cars and use electricity. These fossil fuels release carbon dioxide into the atmosphere, which builds up and creates a blanket effect around the Earth, trapping in heat that would otherwise escape. This trapped heat is causing global climate change and is impacting many species, including polar bears.
On February 26 and 27, the Detroit Zoo will join others around the world in highlighting the challenges that polar bears are facing in the wild. International Polar Bear Day celebrates these majestic creatures while also encouraging the community to not only better understand the impact we have on the environment, but to join us in taking positive action that will help protect vulnerable species.
Each one of us has the power to make a difference. We can change our daily behaviors and use less energy by seasonally adjusting our thermostats, riding our bikes, carpooling with friends or turning off the lights. We can also scale these actions up to our schools or workplaces by encouraging others to join us in this endeavor. Celebrating International Polar Bear Day is a great reason to start, or to take things to the next level.
Our International Polar Bear Day will take place on February 26 and 27 from 11 a.m. to 3 p.m. The events will include zookeeper talks, educational activities and visits with the Zoo’s polar bear mascot. Talini and Nuka, the two polar bears who reside at the Zoo, will receive their usual treats at scheduled times (11:30 a.m., 1 p.m. and 2:30 p.m.) so guests can watch the bears enjoy them. This is not only a great time to visit the Zoo and the more than 2,000 animals living within our 125 acres, but it’s also a chance to learn more about how we can work together to save wildlife and wild places.
– Carla Van Kampen is a curator of education for the Detroit Zoological Society.
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For several years, beginning in 1974, I initiated a study to observe the undisturbed behavior of wild polar bears—hunting, interacting, sleeping, and otherwise just being bears. Collectively, scientists were already accumulating vast amounts of information on polar bear movements by observing where tagged polar bears were recaptured relative to where they were first captured and, later, from the use of satellite radio collars. Similarly, we obtained a great deal of new information from body measurements and specimens collected from bears while they were briefly immobilized for tagging.
However, I felt it was still critical to understand what polar bears spent their time doing when they were not disturbed by scientists in helicopters or Inuit hunters. In other words, I wanted to just let the bears show us, at their own speed, what it meant to be a wild undisturbed bear on the sea in the Arctic.
To do this, we used telescopes from cliff-top observation cabins at Radstock Bay, Devon Island, in the Canadian High Arctic that were high enough that the bears were unaware of our presence. Because of 24-hour daylight in the late spring and early summer, we could watch the bears continuously. Often, we had to take turns between watching inside (and sometimes out in the cold) and sleeping in an unheated tent outside the observation hut. We recorded observations of individual bears non-stop, as long as they didn’t step behind distant land forms or have their visibility obscured by fog.
A cliff-side observation cabin and sleeping tent on Cape Liddon, Devon Island, in spring (©Ian Stirling).
In the spring of 1997, we were extremely fortunate to have the unique and rare chance to witness the complete behavioral sequence of a mating pair of polar bears. Prior to what we learned from our direct observations, it was generally thought that the breeding season was restricted to a period from about early April through the middle of May.
Superficially, one might think the breeding behavior would be quite straightforward: the bears simply have to meet up out on the sea ice at the right time, mate, and sometime later cubs are born. In reality, however, the behaviors and physiological adaptations are highly evolved and definitely not straightforward.
From what we were fortunate enough to learn in 1997, we were able to understand brief observations of bears on the sea ice in Svalbard which enabled me to confirm that breeding behavior continues from the spring through June, and possibly longer.
Finding mates
For starters, most adult females keep their cubs with them for 2 ½ years. Thus, on average, in most years, only about a third of the adult females are even available for breeding. Consequently, adult male polar bears are tasked with locating females that might be available to breed, but range at low densities over vast areas of sea ice.
Thus, males may travel long distances in search of a mate, pausing only to carefully sniff the tracks of any bears they cross in their travels. This is because adult females appear to have glands in their paws that leave a chemical scent capable of informing an adult male that she is potentially available for breeding. When a male detects such a track, he immediately starts following the female until he catches up.
Building trust
However, polar bears don’t just start mating soon after they first meet. Remember that individual adult bears of both sexes are widely dispersed and travel and hunt independently over vast areas on the sea ice most of the time. Thus, female polar bears don’t ovulate spontaneously as the females of many mammals, including humans, do, because, if they did and there was no suitable male close by, the egg would simply die and be wasted. Thus, the females have what is known as induced ovulation which means they will not actually release an egg to be fertilized until they have been accompanied by an adult male for long enough, and with sufficient interaction between them, to stimulate release of the egg at a time when being fertilized is highly likely.
Even after an adult male has located a potential reproductive female, both still have to overcome their biggest behavioral barriers: fear and aggression. Under normal circumstances all adult females, and especially those accompanied by cubs and yearlings, flee from any adult male they meet because of the risk he will kill and eat the cubs. Sometimes an adult male will even kill and eat the female herself, as shown in the photo below.
Dr. Ian Stirling examines an adult female polar bear that was killed and cannibalized by an adult male (©Ian Stirling).
Not surprisingly, the behavioral process necessary to allow sufficient mutual trust to develop so mating can follow is protracted. The first thing a male does after catching up with a lone female in spring is to try to herd her to a location where the chance of encountering another potential competing male is lower, such as an area of rough sea ice, a small isolated bay, the side of a hill on land, or an island. Then, he tries to keep the female in the same restricted area for about a week, while they interact with each other constantly, pausing only to sleep for 7-8 hours each day.
At first, the pair alternately run toward or away from each other, while still being careful not to become too widely separated. They do little or no feeding during this period. As the days pass, the female slowly becomes more trusting of the male and allows him to be closer to her. In return, his behavior becomes progressively less threatening until finally they start simply standing near each other, following each other back and forth, until she finally allows him to make non-threatening physical contact.
The female may reciprocate by initiating non-threatening physical contact with the male. When you remember that normally a female would not allow a male to be anywhere near her for fear of possibly being killed, the development of sufficient trust on her part to allow his intimately close presence represents an essential, but huge, physiological and behavioral adjustment, even if only for long enough to facilitate mating to occur. The male also undergoes a similarly large behavioral change that allows him to behave in a sufficiently unthreatening manner to allow mating to take place.
Mating behavior
Once sufficient trust has been established, after a week or so of interactions, the female will allow the male to mount. Mating then carries on for several periods, sometimes in excess of two hours at a time, for several days in a row. This protracted process appears to facilitate circumstances that are reliable enough physiologically to allow ovulation to occur and the egg to be fertilized.
After mating ceases, the male and female still remain together for an additional day or two, exhibiting tolerant, mellow behavior toward each other that is totally unlike their behavior at all other times of year. These behaviors may include slowly walking together in no particular direction, lying near each other in the snow, or separating, sometimes for as much as a kilometer or more, and then coming back together again, after which the male may again touch the female’s neck or chest with his nose.
An adult female polar bear showing no fear response while being nuzzled by an adult male. (© Mick Brown)
Sometimes, they will simply lie in the snow together (but not touching). Such behavior may give the impression the bears may have actually developed a longer-term attachment to each other. However, it is only a temporary behavioral and physiological adaptation, critical for reproduction to occur, but short-lived. Finally, and unceremoniously, they simply diverge and walk away in different directions.
Repeating the process
Once alone again, the male then begins to search for another female. If he finds one, the process starts all over again. Since only one complete behavioral sequence has ever been recorded in detail, we don’t know if all mating events require a similar commitment of time though it appears from partial observations that they probably do. Considering how long it may take for a male to locate a potential adult female, and then behaviorally engage through the amount of interaction time required before mating may occur, the maximum number of matings a male could undertake in a single year is probably in the range of 4-6.
Because the intensity of competition between adult males is significant and, since larger males are more likely to out compete smaller ones for mating privileges, through natural selection over the longer term, adult males have evolved to be roughly double the size of females.
Until recently, the polar bear’s breeding season was generally thought to take place between early April and mid-May. Probably, a significant contributing factor to determining the mating period was that little hunting by Inuit, or field research by scientists, takes place between late May and the open water season in summer. However, with the advent of ecotourism in Arctic marine areas, particularly in Svalbard, ecotourism ships now regularly enter polar bear habitat from early April through the break-up of the sea ice in early summer. As a result, some of the natural history guides have reliably documented breeding behavior of polar bears through the end of June. Although it is likely that the frequency of mating behavior is significantly reduced by that time, the confirmation of breeding behavior over such a long period is an important revelation.
Because actual mating constitutes such a small part of the total behavioral breeding sequence (≤ 2% of the total time), most casual observers seeing two bears together at distance and behaving as described above, simply did not realize they were observing some part of the sequence of normal mating behavior. Many likely assumed that two polar bears of different size walking about or interacting together were a mother and cub (or were simply confused). However, now that we understand more about the duration, variability, and the overall pattern of the behavioral sequences of “mating pairs,” it has been possible to confirm the full period over which breeding of polar bears in the wild may occur.
An adult female follows an adult male after breeding is completed. In the past, such pairs were sometimes mistaken for a mother with a cub (© Mick Brown).
Delayed implantation
The evolutionary adaptations of polar bears to facilitate successful reproduction are not limited simply to ensuring copulation. After the female has completed mating, the fertilized egg undergoes a small number of divisions before entering a state of dormancy known as delayed implantation. This means that the fertilized egg develops no further but sits in the uterus in a dormant state until autumn when the female’s body “decides” in about October whether it has enough fat stored to be able to have cubs. If the answer is yes, the fertilized egg(s) will then implant and growth of the cubs begins, with birth of the tiny cubs taking place only a couple of months later in about December. If the answer is no, the fertilized egg is either shed or resorbed but we don’t know which at the moment.
There are likely many more almost unbelievable adaptations of polar bears to their polar environment that have yet to be understood. Some will require largely opportunistic extended observations of undisturbed polar bears in wild situations before their significance can be appreciated. However, the more we are able to observe the behavior of undisturbed wild polar bears, the more we will come to understand their incredible adaptations to life in one of the most difficult environments in the world.
Acknowledgements
I am particularly thankful for the long-term support of my behavioral studies of wild free-ranging polar bears from: Department of Biological Sciences at the University of Alberta, Environment Canada, Natural Sciences and Engineering Research Council of Canada, and the Polar Continental Shelf Project. I am also grateful for the opportunities to observe undisturbed polar bears in the pack ice while working for ecotourism companies: Oceanwide Expeditions, One Ocean Expeditions, and Quark Expeditions. I also thank Dennis Andriashek and Cheryl Spencer for their invaluable assistance observing and analyzing the field observations on reproductive behavior.
References for those who might wish to follow up the subject in more detail:
Derocher, A., M. Anderson, Ø. Wiig and J. Aars. 2010. Sexual dimorphism and the mating ecology of polar bears (Ursus maritimus) at Svalbard. Behavioral Ecology and Sociobiology 64:939–946.
Smith, T. G., and J. Aars. 2015. Polar bears (Ursus maritimus) mating during late June on the pack ice of northern Svalbard, Norway. Polar Research 34:25786. (Available here.)
Stirling, I., Spencer, C., Andriashek, D. 2016. Behavior and activity budgets of wild breeding polar bears (Ursus maritimus). Marine Mammal Science 32: 13-37. (Available here.)
Wiig, Ø., I. Gjertz, R. Hansson and J. Thomassen. 1992. Breeding behaviour of polar bears in Hornsund, Svalbard. Polar Record 28:157–159.
Dr. Ian Stirling is a member of the Scientific Advisory Council for Polar Bears International. He is also Research Scientist Emeritus for Environment and Climate Change Canada and Adjunct Professor of the Department of Biological Sciences, University of Alberta.
Banner Image: Dr. Ian Stirling observing polar bears outside on a warm day in early summer at Cape Liddon in Canada’s High Arctic.© Dr. Ian Stirling
This article was originally published by Polar Bears International.
Polar bear breeding begins in the Highlands
The conservation charity, the Royal Zoological Society of Scotland (RZSS), announced today that preparations have begun to allow male polar bear Arktos to meet female polar bear Victoria for the first time. This is the latest and most exciting step in our efforts to support the European breeding programme for this at risk species, which is currently listed as Vulnerable on the IUCN Red List of endangered species.
Arktos (front) & Walker (back) in transportation box
Helping to protect the future of polar bears is not a straightforward task, as it is the loss of sea-ice due to climate change that is the primary threat to the species. Research shows huge uncertainty for the future of polar bears in the wild, with estimates suggesting that the global population could decline by over 30% in just three generations if sea-ice loss continues as projected*. RZSS believes that it has a duty to assist with the establishment of a healthy population of ex-situ animals, not as a substitute for conserving the species in the wild, but to ensure that there will be as broad a range of options for them in the future.
A large 3 by 1.5 by 1.8 metre transportation crate was manoeuvred into position in the male polar bear enclosure on the morning of Friday 19 February and, over the next month or so, eight year old Arktos will be habituated to it. Slowly and steadily, the process will see his keeper’s use positive reinforcement training and his favourite foods to get him used to the new addition to his enclosure. Eventually Arktos will be comfortable enough to enable his keepers at RZSS Highland Wildlife Park to transport him the one mile distance across the Park to Victoria’s enclosure.
Arktos in transportation box
Arktos is expected to travel the short distance to begin his courtship with Victoria around mid-March. A great deal of planning went into the development of Victoria’s enclosure in the Highlands and it was specifically designed with breeding in mind. The enclosure is believed to be unique as it offers maximum animal management flexibility with both a large main enclosure and a smaller holding enclosure, in which Arktos will live separate (but adjacent) to Victoria, until their behaviour indicates that signs are right for the full introduction.
RZSS has become known as one of the leading authorities on polar bears, with its enclosure design and husbandry approach being mirrored by other zoological organisations across the world. In total, RZSS Highland Wildlife Park devotes more space to polar bears than any other zoological institution in the world – over four hectares, or 10 acres, in total – and the enclosures features soft grassy areas, natural slopes, ponds and trees.
Arktos in transportation box
Modern polar bear husbandry has moved on dramatically and these enclosures are unrecognisable from those that were commonplace even up to ten years ago, where many of the negative stories about polar bears in captivity originate. Following comprehensive research by experts in North America and Europe, the zoo community now has an incredibly thorough understanding of both the husbandry requirements of the species and how to care for and improve cub survival rates.
Douglas Richardson, Head of Living Collections at RZSS Highland Wildlife Park, said: “When we first take Arktos to Victoria, he will live in a separate enclosure adjacent to hers. The two bears will be able to communicate and interact through a secure large fence to start with. We fully expect to see them showing an interest in each other right away.
“As with any introduction of large predators, the process must be approached slowly and carefully, paying close attention to positive behavioural indicators, like vocalisations and body posture. Whether we wait until Victoria comes into full breeding condition before mixing them together will depend on how they react to each other in the build-up to that key point.
Female polar bear Victoria
Richardson added: “Polar bear conservation is definitely not simple or easy, but we have an important responsibility. As a conservation body with extensive bear husbandry experience, we truly believe we cannot afford to shy away from the task in hand. If we want to keep all the conservation options on the table for the future of polar bears, we must allow for the idea that a healthy captive population may provide a solution to the species’ plight.
“The birth and rearing of polar bears cubs will be of real value to the overarching breeding programme. As well as helping to highlight the plight of polar bears in the wild, any cubs born in the foreseeable future will remain within the vital safety net of the captive breeding programme. The shrinking polar ice-cap and shortening polar ice season has pitched the species to the forefront of conservation concerns.
Richardson added: “In an ideal world, conservation would happen first and foremost in the wild, but unfortunately this is not the scenario we are dealing with. The next best thing is a combined approach, with in-situ and ex-situ work taking place simultaneously and in a joined up manner. The zoo community has a duty of care to help this species survive and collectively our work is helping to preserve as varied a mix of genes as possible; it will also maintain the option of being able to return animals to the wild at some point in the future. Whilst Victoria’s cubs will never go back into the wild themselves, further down the line her offspring may well play a key role in restoring or augmenting populations in the Arctic.”
