New Field Study Observations Prove Polar Bears Are Thriving
There is irrefutable evidence from Barents and Chukchi Sea subpopulations, among others, that polar bears are fat and reproducing well despite marked declines in summer sea ice over the last two decades.
These indicators of physical and reproductive health, in any species, are signs of thriving populations. [emphasis, links added]
However, these facts negate the premise that polar bears require abundant summer sea ice to flourish, and that creates a problem for polar bear specialists who continue to make that claim (Amstrup et al. 2007; Crockford 2017, 2019).
In other words, the assessment that polar bears are currently thriving is not based solely on estimates of a slight increase in global population size but on published data gathered from field studies on the bears’ physical and reproductive health.
Oddly, biologists repeatedly turn to data from Western Hudson Bay to drive home to the public their preferred message that polar bear health and abundance are being negatively affected by recent summer sea ice declines.
However, they fail to mention that robust field data from many other regions, including the Barents and Chukchi Seas, support the opposite conclusion.
Moreover, wherever possible, they mumble under their breath (or leave out entirely) the fact that poor ice conditions could not be blamed for a 27% decline in polar bear numbers in Western Hudson Bay since 2016 — because their own data showed sea ice conditions have been strong!
Polar bear specialists refuse to update their 2015 global population estimate of 26,000 to reflect recent subpopulation survey results but when those data are taken into account (e.g. Conn et al. 2021; Dyck et al. 2021, 2022; Matishov et al. 2014), the average global population estimate comes to about 32,000 with a wide range of potential error.
Although this modest increase is not statistically significant, it would likely take a 50% increase over that 26,000 estimate to meet that benchmark, considering that a recent 42% increase in Svalbard polar bear abundance was deemed statistically insignificant (Aars et al. 2017).
Although a case has been made that global numbers may indeed be as high as 39,000 (Crockford 2019), that’s not why polar bears are said to be thriving.
Spring research in Svalbard, Norway, in 2022 showed the body condition of male polar bears was stable and the number of females with cubs (both cubs-of-the-year and one-year-old cubs) was up compared to many previous years.
While many bears have abandoned the Svalbard region for less volatile ice conditions in the eastern Barents Sea around Franz Josef Land, the 300 or so that remain are still doing well (Aars 2015, 2018, 2022; Aars et al. 2017; Anderson et al. 2012; Haavik 2022), despite having lost 5-6 times as much summer ice as Western Hudson Bay (Lippold et al. 2019:988; Regehr et al. 2016).
The graph below shows that the number of females with cubs-of-the-year (blue dots) and one-year-old cubs (red dots) were both up slightly in 2022, although overall, neither metric had a significant trend (declining or increasing) over time:
The body condition of adult male bears shown below was down a bit in 2022 but not significantly, and 2019 saw bears in the best condition since 1995 (2020 data is missing):
The body condition of females is not presented in the annual records posted by Norwegian researchers, but Jon Aars stated in 2022 that females were in excellent condition, continuing the trend documented in a 2019 published study (Lippold et al. 2019).
“Unexpectedly, the body condition of female polar bears from the Barents Sea has increased after 2005, although sea ice has retreated by ∼50% since the late 1990s in the area, and the length of the ice-free season has increased by over 20 weeks between 1979 and 2013. These changes are also accompanied by winter sea ice retreat that is especially pronounced in the Barents Sea compared to other Arctic areas” [Lippold et al. 2019:988, my bold]
Read rest at Polar Bear Science
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