Why does a black rhino have to hang upside down when it takes a flight? Can't it just lie flat?

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Classic brain teaser: How many steps does it take to put an elephant in the refrigerator? The answer is three steps - open the refrigerator, put the elephant in, and then close the refrigerator door.

Please use your imagination to think about how to transport a large animal like a four-ton elephant or rhino. If only the answer was as simple as a brain teaser!

Despite the word "black" in its name, the black rhino is more grey in colour and is generally used to distinguish it from the white rhino.

Image source: Wikipedia

Robin Radcliffe, a senior wildlife researcher, and others perfectly answered this question in a research paper published in the Journal of Wildlife Diseases in March 2021, hoping to understand the impact of transporting black rhinos (Diceros bicornis) in an upside-down position after being dazed by anesthetics on their bodies.

Although this research seems a bit ridiculous, it has achieved great success in practical application and also won the Ig Nobel Prize in Transportation in 2021.

Many people may wonder why we need to study how to transport black rhinos? Isn't it good for black rhinos to live peacefully in their hometown?

Scholars at Cornell University in the United States once gave the answer: the main reason is that with poachers becoming more and more rampant today, transferring them to sparsely populated wilderness can save them from the crisis of being hunted; in addition, although black rhinos will be temporarily lost due to being in an unfamiliar environment by being artificially transported to different habitats, they will soon get acquainted with rhinos of the opposite sex, which can enrich the diversity of the species and the gene pool to a certain extent.

How rare are black rhinos? In the 20th century, black rhinos were the most numerous of all rhino species. However, due to severe poaching in Zimbabwe, the number of black rhinos dropped sharply in the second half of the 20th century, from 70,000 to 10,000-15,000 in 1981. Just ten years later, the number dropped to less than 2,500, and was listed as an endangered species by the International Union for Conservation of Nature (IUCN), while the western black rhino (Diceros bicornis longipes) has completely become extinct.

The little rhino is so cute when it runs!!

Image source: gifer

In order to better protect these huge endangered creatures, people have to take some measures. For example, after injecting anesthesia or sedation into black rhinos, they are transported to remote areas with few people by helicopter. However, for many years, for these large mammals that have been moved around, people have rarely understood the possible harm to them caused by sedation drugs, transportation methods, and different postures during transportation.

For example, the injections that can turn giant black rhinos into "sleeping cows" in a second are mostly opioids, which may cause some side effects (shortness of breath, reduced oxygen content in the blood, and accelerated metabolism, etc.). In other words, artificial migration, which was originally well-intentioned, may have greater hidden dangers than poaching. At the least, it may damage the health of black rhinos, and at the worst, it may cause the number of black rhinos, which is already small, to decrease further.

But after comprehensive consideration, the researchers believed that the black rhinos still needed to be injected with sedatives, so they began to focus their research on the posture of the black rhinos during transportation.

Black rhinos are also afraid of heights?? That’s why they need to wear blindfolds??

Image source: Reference [1]

The researchers anesthetized twelve black rhinos weighing between 802 kg and 1233 kg, and then hung them in a side-lying position for ten minutes. They then used a crane to hang them upside down with their four limbs in the air for ten minutes to compare which of the two postures was safer for transporting black rhinos.

From the physiological indicators of black rhinos, whether lying on their side or hanging upside down, black rhinos have significant hypoxemia (inadequate oxygen in the blood) and hypercapnia (increased carbon dioxide concentration in arterial blood due to insufficient ventilation or excessive carbon dioxide production). When the black rhinos were hanging upside down with their legs upside down, the average arterial oxygen partial pressure was 42 mmHg, 4 mmHg higher than when lying on their side, and the arterial carbon dioxide partial pressure was 52 mmHg, 3 mmHg lower than when lying on their side.

Although the two postures do not significantly damage the black rhino's lung function, hanging upside down with all four legs in the air puts relatively less pressure on the black rhino's chest cavity, allowing the spine to stretch better, and the amount of air inhaled is also slightly increased, making breathing relatively smoother; if the black rhino remains lying on its side, the large amount of blood flowing in the lower part of the lungs for gas exchange will be compressed due to gravity.

You think it's comfortable to let the black rhino lie down to be transported to the destination, but the actual effect is not as good as you think

Image source: Reference [1]

So, with their limbs tied up with ropes and their eyes covered with masks, they are hung upside down under the helicopter, swaying and swaying in the wind during the journey. If they are unlucky, they may even hit a few blind flying birds - this has become a daily routine for rhinos when flying on airplanes.

From the perspective of transportation carrier and method, hanging black rhinoceros means:

1. Easier to fix: When a rhino is lifted while lying down, the stretcher adds extra weight, and a six-person team may take up to 30 minutes to position and secure the rhino to the platform, compared to just a few minutes to tie ropes around the animal's legs and feet.

2. Lower doses of anesthetics: Conservation organizations no longer need to inject rhinos with massive amounts of drugs to get them through the long and tortuous journey.

3. Faster migration: A long time ago, most rhino migrations were carried out by truck, but some remote areas cannot be reached by road, and land transportation and other methods will bring time and economic uncertainty to transportation.

4. Better adaptability: It only takes half an hour for the rhino to successfully reach its new home. Thanks to the blindfold, the rhino didn’t even know it had been in the air after getting off the plane...

Image source: pixabay

Radcliffe said that although the physiological differences between the two postures of transportation were not significant in this study, any small changes are enough to help us improve the safety of wild animal transportation, and at the same time, allow us to choose and think about animal welfare more humanely.

Dr. Franken, an African wildlife conservation expert, also said: "The most beautiful picture I have ever seen in Africa is a three-year-old male rhino swaying in the afterglow of the sunset towards a world without gunfire."

......

Rhino A: If you're kidnapped, just blink!

Rhino B: How can I blink when I'm blindfolded?

References:

[1]Radcliffe RW, Jago M, Morkel PV, Morkel E, du Preez P, Beytell P, Kotting B, Manuel B, du Preez JH, Miller MA, Felippe J, Parry SA, Gleed RD. THE PULMONARY AND METABOLIC EFFECTS OF SUSPENSION BY THE FEET COMPARED WITH LATERAL RECUMBENCY IN IMMOBILIZED BLACK RHINOCEROSES (DICEROS BICORNIS) CAPTURED BY AERIAL DARTING. J Wildl Dis. 2021 Apr 1;57(2):357-367. doi: 10.7589/2019-08-202. PMID: 33822147.

[2]https://zh.wikipedia.org/wiki/%E9%BB%91%E7%8A%80

Reprinted from: Bringing Science Home

Written by: Ah Xian

Editor: Guru