Risk to Alaskan polar bear cubs from oil exploration in coastal Wildlife Refuge is small

From Dr. Susan Crockford’s Polar Bear Science

Posted on August 18, 2020 |

A bill recently introduced to US Congress (30 July 2020) is supposedly meant to “safeguard the Beaufort Sea polar bear’s denning habitat”.  However, the bill is named the “Polar Bear Cub Survival Act”, which tells us this is an appeal to emotions rather than a call for rational decision-making. In fact, few Southern Beaufort Sea polar bear cubs are born on land in the Alaska National Wildlife Refuge and the risks to them from oil exploration is not overwhelming.

Amstrup_only solution_with 3 cubs_Oct 8 2014Amstrup_only solution_with 3 cubs_Oct 8 2014

Despite a modest decline in summer sea ice since 1979, only about half of Southern Beaufort Sea polar bear females currently make their dens on the sea ice in late fall. Recent research confirms results from older studies that show denning females in Alaska are highly tolerant of the kind of disturbance associated with oil exploration and few dens are found more than about 1 km from the shore. This emotion-laden bill is not really about protecting polar bears: it’s a political move aimed at preventing oil exploration along the coast of Alaska after previous efforts failed. It comes ahead of an announcement today (18 August 2020) that the White House will begin to auction off leases for oil drilling in the ANWR.

Don’t let the ‘trust my word, I’m an expert’ hyperbolic testimony from activist scientists like Steven Amstrup and others hold sway on this issue – see for example “Alaska polar bear den disturbances part of ‘death by a thousand cuts,’ researcher says“ (biologist Wesley Larson on Alaska Public Radio, 14 July 2020), or activist conservation organizations Polar Bears International and World Wildlife Fund. Have a look at the facts on the matter taken from the published literature, which I summarize below (as many pdfs provided as possible).

Alaska National Wildlife Refuge

The ANWR is outlined in red and the small portion of the area proposed for oil exploration is 1002 in yellow. NPR-A (‘National Petroleum Reserve’) is the area around Prudhoe Bay that’s already under extraction (and therefore has actual data on polar bears and other species with respect to their responses to oil exploration and extraction). Most oil exploration is done in winter to avoid the muck that melted permafrost generates, raising concerns that oil-associated activities may put polar bear cubs at risk if they are born in dens along the coast that become hidden by accumulated snow.

Southern Beaufort Sea subpopulation

Amstrup et al 2005_Fig 1 map of CS_SB_NB boundariesAmstrup et al 2005_Fig 1 map of CS_SB_NB boundaries

The Southern Beaufort polar bear subpopulation (SB) stretches across the North Slope of Alaska and western Canada (map above from Amstrup et al. 2005), although a change in the eastern boundary to just east of Tuktoyaktuk (~133oW) has been tentatively accepted (see Crockford 2020). There is much mixing of Southern Beaufort bears with Chukchi Sea bears in the west and Northern Beaufort bears in the east which has always made counting the SB population difficult.

The Southern Beaufort subpopulation is often touted as one of the most threatened group of polar bears in the world, based almost exclusively on a population survey published in 2015 that suggested the SB polar bear population declined by 25-50%, from 1,526 to 907 bears (Bromaghin et al. 2015). See my latest book for a full discussion of this issue (also Crockford 2017, 2020) but the most critical failure, in my opinion, was that the 2001-2010 study failed to take into account the devastating effects on polar bears from thick spring ice conditions during 2004-2006 (e.g. Stirling 2002; Stirling et al. 2008). Moreover, polar bear biologists continue to imply that the population decline was due to loss of summer ice.

The report on polar bears by the Committee on the Status of Endangered Wildlife in Canada published in June 2019 (COSEWIC 2018: 39-41) acknowledged problems with the 2010 estimate generated by Bromaghin and colleagues. They proposed an ‘equally valid’ estimate for SB of 1,215 bears at 2006. This estimate of 1,215 bears is currently the one used by the joint Inuvialuit/government body charged with managing SB and NB subpopulations in Canada. While the PBSG considers SB to be ‘likely decreased’ (Durner et al. 2018), many Inuit in the Canadian portion of the region feel that polar bear numbers have been stable or increased within living memory (Crockford 2020).

Despite known problems with the 2001-2010 SB survey and the fact that it is now 10 years out of date, polar bear researchers like Steven Amstrup (e.g. Amstrup 2019) still suggest that the SB population has continued to decline. On the contrary, US biologists conducted a polar bear survey for the Chukchi Sea and the Alaska portion of the Southern Beaufort in 2016 and estimated that 4,437 (range 2,283-9,527) bears lived in the region, of which about 3,000 were in CS and 1,437 in the Alaskan portion of the SB: that’s about 3X the size of the Southern Beaufort polar bear population in Alaska (about 450) estimated by Bromighan and colleagues in 2010 (AC SWG 2018; Regehr et al. 2018). A new population survey for the entire SB is supposedly ongoing but no results have been forthcoming (Crockford 2020).

Southern Beaufort Sea summer ice cover has declined only 1.75 days per year in the 37 years between 1979 and 2015 – just over 2 months, compared to the 5 1/2 months lost in the Barents Sea (Regehr et al. 2016), where polar bears are currently thriving. Meanwhile, abundant photographs of fat polar bears, including females and fat yearlings like the one below,  from a government survey during the summer of 2019 belie the claim that the Southern Beaufort polar bear subpopulation is the “most threatened of all” or that it is “on the verge of collapse.

Mother and two-year-old cubs resting onshore SB_NOAA summer 2019Mother and two-year-old cubs resting onshore SB_NOAA summer 2019

Terrestrial denning in SB

Polar bear biologists are quite aware that most of the Southern Beaufort population does not come near land at all and only about half of all pregnant females make their maternity dens on or near shore (Pagano et al. 2019; Olson et al. 2017).Polar Bear (Sow), Arctic National Wildlife Refuge, AlaskaPolar Bear (Sow), Arctic National Wildlife Refuge, Alaska

Polar Bear (Sow), Arctic National Wildlife Refuge, Alaska

The issue being debated is not about bears who come onshore during the summer but about the females that spend winter on shore in maternity dens. Compare this finding regarding bears on land in summer, from 2019:

“…approximately 15–27% of the subpopulation comes on land in the summer (hereafter “land bears”) while the remainder follows the retreating sea ice over the deep waters of the Arctic Basin (hereafter “ice bears”) (Atwood et al. 2016, Pongracz and Derocher 2017, Wilson et al. 2017).” [Pagano et al. 2020, introduction, my bold]

To this, from 2007:

Our tracking data indicated that pregnant polar bears made little use of whale remains and that use was not associated with coastal denning. [Fischbach et al. 2007:1401, my bold]

In other words, abundant whale remains in recent years have not been luring more females ashore than usual and causing them to stay and make dens nearby when they otherwise might not: a few pregnant bears come ashore later in the fall to settle into a den location with the intension of staying for the winter.

Den Surveys

A recent ‘terrestrial’ den survey (Smith et al. 2020 Fig. 1, copied below) in the National Petroleum Reserve along the North Slope around Prudhoe Bay found only 33 dens in the twelve years between 2004 and 2015 (less than 3 per year), of which more than half were on nearshore sea ice or on an offshore barrier island (these locations are all considered ‘terrestrial’ dens)(Amstrup and Gardner 1994:3). Some den locations appear to have been used in more than one year. This study region, shown in the map below, is larger than the proposed 1002 oil exploration area of the ANWR and therefore likely to contain even fewer polar bear dens on land in any one year. And while it is likely that there are more dens than biologists can locate, the total number in any one year is still fairly small relative to the number found along the entire coast and in the offshore pack ice.

Smith et al. 2020 fig 1 polar bear dens S BeaufortSmith et al. 2020 fig 1 polar bear dens S Beaufort

Two studies have compared pack ice vs. terrestrial denning rates in the Southern Beaufort. In 1998-2005, 120 polar bear dens were found during the eight years across the entire Southern Beaufort subpopulation region from the Chukchi Sea to western Canada (about 15 per year for the entire region). Of these, 63% of dens were found in ‘terrestrial’ locations (on land or nearshore ice) and 37% were well out on the pack ice, while during an earlier period (1985-1994), the proportions were virtually opposite (38% on land vs. 62% on pack ice)(Fischbach et al. 2007:1399). However, a more recent study found that from 2007-2013, only 55% of bears made terrestrial dens (Olson et al. 2017): much less than the 63% found during the previous period (1998-2005) by the Fischbach study.

Risks from oil exploration

This is what I wrote in the 2019 State of the Polar Bear Report (Crockford 2020) about the concerns over oil interests in the National Wildlife Refuge Alaska (ANWR) along the North Slope of Alaska:

…biologists have found that while females are generally loyal to either land or sea for denning, as well as to a particular stretch of coast, they were not loyal to a specific place. Such flexibility is probably necessary because annual variations in weather, sea ice conditions and prey availability have always impacted bears’ choice of where to den.282 In other words, there is strong evidence to suggest that if drilling or other activities were to disturb a pregnant female at a particular den location one year, she simply would not try to den in that spot again. Moreover, it is unlikely she would den in the same spot even if she was not disturbed. In addition, the small proportion of the polar bear population that spends some part of the summer on land are concentrated at the whale bone piles at Kaktovik and a few lesser known beach sites, which should be easy for drilling and exploration crews to avoid.283

It is worth mentioning that earlier oil exploration and extraction activities – from the 1990s in the Eastern Beaufort (around Tuktoyaktuk in Canada) and from the 1970s in the Canadian High Arctic – were expected to cause a marked increase in the number of defense kills and unacceptable disruptions to denning.284 But impacts on polar bears have been so minimal that we’ve heard virtually nothing about them.285Similarly, there has been the potential for oil-related activities to cause disruption to denning outside the ANWR, a little further west along the Alaskan coast at Prudhoe Bay in the National Petroleum Reserve (the largest oil field in the USA). But since exploration and extraction began at this site in the 1960s,286 there have been virtually no problems with polar bears (either from disruption of feeding and denning activities or due to excessive defense of life or property kills).287 More specifically, biologist Steven Amstrup looked at 20 polar bear dens located within the ANWR between 1981 and 1992 and found that, contrary to expectations, virtually all females were exceptionally tolerant of the kind of human activities associated with oil exploration and drilling (including aircraft, snow machines, seismic surveys, and oil field operations).288

Overall, documents show the oil industry in Alaska and western Canada has a very good track record of dealing responsibly with polar bears through a combination of education and precautionary practices. 289

I would add to this that new research (Larson et al. 2020) has determined denning females were highly tolerant to distrubance: only 11 females (out of 138, from more than 40 years worth of data, 1975-2017) left their dens because of disturbance (which was almost always because of aircraft flying overhead): see Polar Bear Moms Stick to Their Dens Even Faced With Life-Threatening Dangers Like Oil Exploration“]. The worry being advanced is that this reluctance to abandon a den would result in a few females being threatened by an oncoming heavy vehicle that might run over the den and annihilate her cubs. A review of a proposed Winter Seismic Survey on the Coastal Plain by SAExplorations, written by Steven Amstrup from the activist organiziation Polar Bears International, estimated a 25% chance that at least one polar bear will be crushed to death in one season of seismic surveys in ANWR (Amstrup 2018b).

However, Amstrup and Gardner (1994:8) stated in regards to the risks faced by pack-ice denning bears:

“Contrary to previous hypotheses (Stirling and Andriashek 1992), substantial polar bear denning occurs in the Beaufort Sea region of northern Alaska and adjacent Canada. Bears that den on pack ice are subject to risks not encountered by bears that den on land. Unstable, moving ice caused early abandonment of dens and, apparently, loss of cubs. However, the persistence of pack-ice denning indicated that those risks are not overwhelming. [my bold]

I suggest that the potential risks from oil exploration to those few polar bear cubs whose mothers make dens on land in the ANWR (less than a handful every year) are similarly ‘not overwhelming’. The small risk involved from oil exploration (especially given the track record of the industry in Alaska) does not threaten the survival of the entire Southern Beaufort population, which appears to have largely recovered from the population decline of 2004-2006. The proposed legislation to protect Southern Beaufort Sea polar bear cubs introduced by Jared Huffman (D-San Rafael) on 30 July 2020 is an emotional ploy meant to hamstring US oil production: this bill is about the politics of oil, not polar bear conservation.

Footnotes from Crockford 2020 quote (#s 282-289):

282 Amstrup and Gardner 1994; Garner et al. 1990.
283 Atwood et al. 2016b; Heereman and Peacock 2013; Miller et al. 2015; Rogers et al. 2015; Schliebe et al. 2008.
284 Amstrup and Gardner 1994; Stirling et al. 1977b.
285 An employee was mauled by a bear at the Imperial Oil exploration site in January 1975 and the bear was later shot and killed (Montreal Gazette, 8 January 1975, pg. 2: ‘Man mauled by polar bear’); in August 2011, a bear was shot by a security guard at a BP oil field, see https://polarbearsinternational.org/news/article-polar-bears/polar-bear-death-at-oil-field-investigated/
286 https://www.epmag.com/prudhoe-bay-once-lifetime-discovery-779816
287 National Research Council 2003, pp 103–104; Fischbach et al. 2007.
288 Amstrup 1993.
289 Truett 1993.


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August 19, 2020 at 04:25PM

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