Science And The Polar Bear

Question: Does the best available science on polar bear populations support listing them as "threatened" under the Endangered Species Act (ESA) and would such listing really help the polar bear?

Answer: No. In fact, science shows that the population of polar bears have increased over the past 30-40 years with the aid of international agreements that limit hunting and a focus on conservation. Many of the scientific findings citied by political activists are flawed, and wildlife biologists from the State of Alaska say that listing the Polar Bear as "threatened" could actually harm polar bear conservation efforts.

Furthermore: Subjecting the polar bear to ESA rules would give Washington bureaucrats unprecedented power over business activities, private property rights and individual freedom in ALL 50 STATES. Low-income consumers would almost certain see their energy costs skyrocket.

Here Are The Scientific Facts ...

The polar bear population has doubled over the last 40 years. Click for details and cites.
The science is inclusive regarding the impact to polar bears of the ‘potential’ loss of sea ice. Click for details and cites.
A polar bear listing would have negative impacts on sustainable management programs aimed at helping polar bears. Click for details and cites.
There is a clear lack of sound science in the polar bear listing petition. Click for details and cites.

1. The Polar Bear Population Has Doubled Over the Last 40 Years

Polar bears are currently managed in healthy numbers and, in fact, are currently at historic high population levels of two to three times the population of 30-40 years ago.
- 1965: About 10,000 (IUCN 1966)
- 1967: About 10,000 (Schuhmacher 1967)
- 1972: Roughly estimated at 20,000 (DeMaster & Stirling 1981)
- 1983: Perhaps 20,000 (Nowak & Paradiso 1983)
- 1996: 20,000 - 30,000 (Watson 1996)
- 1997: 22,000 - 27,000 (Garner 1997)
- 1998: 22,130 - 27,030 (Truett & Johnson 2002)
- 2001: At least 22,000 (Schliebe 2001)
- 2002: 21,500 - 25,000 (Lunn et al. 2002)
- 2005: 20,000 - 25,000 (Polar Bear Spec. Gr. 2005)
- 2006: 20,000 - 25,000 (IUCN 2006)
Source: Paul Massicot; ; Animal Info © 1999 - 2006 www.animalinfo.org/species/carnivor/ursumari.htm
"The total number of polar bears worldwide is estimated to be 20,000-25,000. See: Federal Register, Vol. 72, No. 5/ Tuesday, January 9, 2007, p. 1068) For full report, go here.
Full and complete polar bear population estimate is just that, estimates, with most information either incomplete due to "absence of abundant data" or "statistically insignificant" data on most populations. Thus, population "status and trend cannot be determined" for the polar bear in many regions. A few examples from the proposal to list the polar bear as threatened follow:
- "East Greenland population number is unknown since no population surveys have been conducted in the past."
- "Because only one abundance estimate [of the Barents Sea Population] is available, the status and trend cannot yet be determined."
- "The Kara Sea population number is unknown because population surveys have not been conducted."
See: Federal Register, Vol. 72, No. 5/ Tuesday, January 9, 2007, p. 1070) For full report, go here.
"Based on the report "Bears: Status Survey and Conservation Action Plan," issued by the World Conservation Union (IUCN), polar bear populations are in no immediate danger except for one or two groups on the West cost of Greenland which are subjected to excessive hunting. All of the other populations which have been documented are either stable or increasing." Source: "The Polar Bears of the Hudson Bay, Miceal O’Ronain, December 29, 2002 (http://www.john-daly.com/p-bears/index.htm)
According to the ICUN, “Globally, less than one-third of the 19 known or recognized polar bear populations are declining, more than one-third are increasing or stable, while the remaining third have insufficient data available to estimate population trends and their status has not been assessed. Two of these polar bear populations occur within U.S. jurisdiction.”
Source: CRS Report RL33941, Polar Bears: Proposed Listing Under the Endangered Species Act, by Eugene H. Buck, (March 27, 2007), p 1. For full report, go here.
The only population with long-term trend data that is declining with any statistical confidence is the Western Hudson Bay population. The Southern Beaufort Sea population is claimed to be declining but it is not ‘statistically significant’ because previous population counts had broad confidence intervals. "With the exception of the Western Hudson Bay population, the Southern Beaufort Sea population has the most complete and extensive time series of life history dating back to the late 1960's...The precision of the earlier [Southern Beaufort Sea population] estimate of 1,800 polars was low, and consequently the 2006 estimate of 1,526 is not statistically significantly different." (Source: Amstrup, et al. 2001, p.230. See: Federal Register, Vol. 72, No. 5/ Tuesday, January 9, 2007, p. 1076.) For full report, go here.
The general population status of polar bears is currently stable, though there are pronounced differences between the various populations. Some populations are stable, some seem to be increasing, and some are decreasing due to various pressures. The status of many populations is not well documented. Source: The Polar Bears of the Hudson Bay, Miceal O’Ronain, December 29, 2002)
During the proceedings of the 14th Working Meeting of the IUCN/SSC Polar Bear Specialist Group, it was noted that while the noting that the decline of Western Hudson Bay polar bears went from approximately 1,200 in 1987 to less than 950 in 2004. However, their own studies showed a harvest rate of 45 per year. This harvest rate is more than enough to account for all of the decline that was seen. (Source: Proceedings of the 14th Working Meeting of the IUCN/SSC Polar Bear Specialist Group, Occasional Paper of the IUCN Species Survival Commission (Page 34-35).
Traditional ecological knowledge also suggested that the subpopulation [of Davis Straight polar bears] had increased over the last 20 years. The principal justification for this adjustment is based on the observation that the annual harvest has been sustained for the last 20 years and on non-quantitative observations that continue to suggest the subpopulation has increased. Source: Proceedings of the 14th Working Meeting of the IUCN/SSC Polar Bear Specialist Group "Global Status and Management of the Polar Bear" (Page 258-259) For full report, go here.
Greenland, who has a history of significant over-harvesting of polar bears, has just implemented quotas to be implemented and enforced as of January 1, 2006. Thus, it is unclear what effect past over-harvesting has had on population levels. (Source: Polar Bear Specialist Group of the IUCN Species Survival Commission. (Page 133) For full report, go here.
Significant harvest levels, also unregulated, have been occurring in Chukotka, Russia. (Source: Polar Bear Specialist Group of the IUCN Species Survival Commission. (Page 155). For full report, go here

2. The Science Is Inclusive Regarding Impact To Polar Bears Of The ‘Potential’ Loss Of Sea Ice

USFWS indicates that the arctic is warming and that sea ice is currently diminishing, thus causing, in the opinion of USFWS, a ‘potential’ future threat to the polar bear. However, "polar bears do not use the majority of the ice cap -- instead, they favor near-shore ice." "Polar bears are adaptable to use land for hunting and to den, and data from several areas indicate that bears are already adapting." "And, polar bear survival may be... more dependent on snow for denning than on the presence of sea ice." (Source: Testimony in Alaska to review listing the polar bear as an endangered species, Tina Cunning, Special Assistant to the Commissioner Alaska Department of Fish and Game).

USGS study used to support listing cites no clear impact on sea ice coverage and says more date is needed. "In our analysis of the 2001–06 data, we did not find clear evidence for a relationship between sea ice coverage in the SBS region (i.e., the covariate ice) and survival. However, this should be interpreted in light of the short duration of the study and the limitations of the data. Source Polar Bear Population Status in the Southern Beaufort Sea. Source: Eric V. Regehr and Steven C. Amstrup, U.S. Geological Survey; and Ian Stirling, Canadian Wildlife Service, Open-File Report 2006-1337 P. 12.

Studies show that Polar Bears rely on snow pack for denning to birth and raise cubs, not sea ice. "Over much of their range, female polar bears den in a pattern where individual dens are scattered over broad reaches of habitat at low density. All denning areas (e.g. mountains, and coastal and river banks) have topographic characteristics that predictably catch snow in the autumn and early winter, where a pregnant female can create a snow cave early in winter and subsequently be covered over. Maternity dens are often dug on slopes of 20 - 40 deg where snow has accumulated to depths of 1 - 3 m (3.3 - 9.8'). Across the range of the polar bear, most denning, whether in concentrated areas or dispersed, occurs relatively near the coast (within 10 - 20 km (6 - 12 mi) of the coast)." (DeMaster & Stirling 1981, Amstrup 2004) Source: Paul Massicot; ; Animal Info © 1999 - 2006 www.animalinfo.org/species/carnivor/ursumari.htm
“Although some scientists predict the extinction of polar bears under potential climate change scenarios, not all sea-ice changes will harm polar bears. For example, reduced sea ice thickness and coverage in far northern regions is likely to improve polar bear habitat.
Source: A. E. Derocher, N.J. Lunn, and I. Stirling, “Polar Bears in a Warming Climate,” Integrative and Comparative Biology, v. 44, no. 2 (Apr 2004): 163-176.
“Others remind biologists that climate-related changes to a species’ distribution does not necessarily result in changes in abundance.” Source: C.J. Krebs and D. Berteaux, “Problems and Pitfalls in Relating Climate Variability to Population Dynamics,” Climate Research, v. 32 (2006): 143-149.
Greenland is subject to frequent and extreme temperature changes. For example, a 136-year temperature history for the area about Ilulissat Greenland finds that from the 1860s to the 1930s the temperature in the vicinity of Ilulissat was increasing; however, since the 1940s the temperature in the vicinity of Ilulissat has been decreasing. Source: Miceal O'Ronain, Greenland Melting?, Cambridge-Conference Network, October 29, 2002.
USFWS cites others studies concluding that, “as a species, the polar bear have survived at least two warming periods.” These studies also conclude that “the precise impacts of these warming periods on polar pears and Arctic sea ice habitat are unknown.” Source: Dansgaard et al. 1993, p. 218., as seen in the Federal Register, Vol. 72, No. 5/ Tuesday, January 9, 2007, p. 1081. For full report, go here

"There is no evidence to suggest that ice in the Arctic Basin disappeared entirely during either of these warm periods or that any ice-dependent species disappeared. Polar bears and their primary prey existed before the last Ice Age and significant populations of them remain today. The tight association of polar bears and their prey species with moving sea ice gives them a flexibility that land-based carnivores do not have." Source: CRS Report RL33941, Polar Bears: Proposed Listing Under the Endangered Species Act, by Eugene H. Buck, (March 27, 2007), p 10. For full report, go here.

The US Fish & Wildlife Service (USFWS) describes how the southerly populations are experiencing stress from ice free periods and other populations, such as the Southern Beaufort, “will, or are currently, experiencing initial effects of changes in sea ice." This latter discussion breaks the 19 sub-populations into three categories, according to how soon they might be affected by loss of sea ice in late summer. However, "[The] more northerly populations are expected to be affected last due to the buffering effects of the island archipelago complex, which lessens effects of oceanic currents and seasonal retractions of ice and retains a higher proportion of heavy, more stable multi-year sea ice." This is another reason why the polar bear species does not qualify to be considered “threatened’ throughout all or a significant portion of its range within 45 years. (Source: Aars et al. 2006. Federal Register, Vol. 72, No. 5/ Tuesday, January 9, 2007, p. 1080). For full report, go here

3. A Polar Bear Listing Would Have Negative Impacts On Sustainable Management Programs and International Conservation Agreements

“We are concerned that a listing of polar bears under ESA in the United States may actually be harmful for the conservation of polar bear populations internationally. Numerous federal, Canadian provincial, and Alaska agencies have considerable expertise on arctic populations. Ongoing conservation at an international level is consistent with current international agreements and will provide for proactive monitoring and research toward the long term health of all arctic populations.” (Source: Testimony in Alaska to review listing the polar bear as an endangered species, Tina Cunning, Special Assistant to the Commissioner Alaska Department of Fish and Game).

“Internationally, the multilateral 1973 Agreement on the Conservation of Polar Bears and the 2000 bilateral Agreement Between the Government of the United States of America and the Government of the Russian Federation on the Conservation and Management of the Alaska-Chukotka Polar Bear Population provide a basis for cooperation on polar bear management. In addition, Alaska and Canada exercise joint cross-border management through the Inuvialuit-Inupiat Polar Bear Management Agreement for the Southern Beaufort Sea.” Source: CRS Report RL33941, Polar Bears: Proposed Listing Under the Endangered Species Act, by Eugene H. Buck, (March 27, 2007), p 3. For full report, go here.

In addition, polar bears are listed on Appendix II of the Convention on International Trade in Endangered Species of Fauna and Flora (CITES), which contains species not necessarily threatened with extinction but requiring controlled trade to prevent population declines, as well as other species whose body parts are difficult to distinguish by visual inspection (the so-called “look-alike” problem, in this case in controlling trade in bear gall bladders).13 ESA implements CITES provisions domestically. As such, ESA affords protection to endangered species and wildlife of global concern. To complement CITES, ESA specifically prohibits interstate and foreign commerce in ESA-listed species. FWS agents and inspectors work to control any illegal trade and international movement of CITES- and ESA listed species, since some species found in other countries may be brought into the United States by activities that could threaten their long-term survival. Source: CRS Report RL33941, Polar Bears: Proposed Listing Under the Endangered Species Act, by Eugene H. Buck, (March 27, 2007), p 3-4. For full report, go here.

“Under ESA, the Secretary is required to take into account foreign polar bear conservation programs, including conservation hunting programs involving non-local (including U.S.) hunters. However, an ESA listing as “threatened” triggers an automatic listing as “depleted” under the MMPA, a listing that would prevent U.S. citizens from importing polar bear products into the United States. Such an import ban, effectively stopping U.S. participation in conservation hunting programs, is likely to seriously compromise successful Canadian community-based conservation programs.” Source: M. M. R. Freeman and G. W. Wenzel, “The Nature and Significance of Polar Bear Conservation Hunting in the Canadian Arctic,” Arctic, v. 59, no. 1 (2006): 21-30. (Quoted in CRS Report RL33941, Polar Bears: Proposed Listing Under the Endangered Species Act, by Eugene H. Buck, (March 27, 2007), p. 7). For full report, go here.

The FWS acknowledges that “the 1973 Polar Bear Agreement is viewed as a success in that the Polar Bear populations recovered from excessive harvests and severe populations reductions." (Original Source: Polar Bears International - Polar Bears in Depth. Cited in the Federal Register, Vol. 72, No. 5/ Tuesday, January 9, 2007, p. 1086). For full report, go here

4. There Is A Clear Lack of Sound Science In The Polar Bear Listing Petition

In regard to the information provided as justification, "We are concerned that some scientific information may have been omitted or may not have been evaluated in preparing the draft rule." (Source: Testimony in Alaska to review listing the polar bear as an endangered species, Tina Cunning, Special Assistant to the Commissioner Alaska Department of Fish and Game).
We question the computer modeling and analysis "should more fully address the adaptability of polar bears, alternate food sources, alternate denning options, and climatic conditions." (Source: Testimony in Alaska to review listing the polar bear as an endangered species, Tina Cunning, Special Assistant to the Commissioner Alaska Department of Fish and Game).

Not Enough Data to prove that the Southern Beaufort Sea Bear population is declining. "Because precision of earlier estimates was low, our current estimate of population size and the earlier ones cannot be statistically differentiated. Polar Bear Population Status in the Southern Beaufort Sea. Source: Eric V. Regehr and Steven C. Amstrup, U.S. Geological Survey; and Ian Stirling, Canadian Wildlife Service, Open-File Report 2006-1337 P. 1.

“There may be several reasons for the observed changes, including changes in sea ice; those who conduct population censuses of polar bears will need to be cautious in interpreting whether apparent population variations are indicative of different habitat use (e.g., greater numbers of bears onshore) or actual changes in population abundance.” Source: CRS Report RL33941, Polar Bears: Proposed Listing Under the Endangered Species Act, by Eugene H. Buck, (March 27, 2007), p 5. For full report, go here.

“Others suggest that there is considerable uncertainty in the estimates of polar bear population numbers and trends as well as in our understanding of polar bear habitat. Much of what we know about the polar bear habitat is confined to regions close to shore that have been studied during long summer days, with little known about what happens on drifting sea ice far from shore, especially in winter when there is little or no daylight. These critics also urge caution on interpreting studies of sea ice change that are based primarily on surveys of nearshore regions, rather than the drifting sea ice environment in the central Arctic Basin, where ice may be thickest. Recent studies conclude there is significantly more variability in ice thickness between years and regions than is predicted by climate models, which means that ice thickness can increase or decrease rapidly as well as differ among regions.” Source: Seymour Laxon, Neil Peacock, and Doug Smith, “High Interannual Variability of Sea Ice Thickness in the Arctic Region,” Nature, v. 425 (Oct. 30, 2003): 947-950 (Quoted in CRS Report RL33941, Polar Bears: Proposed Listing Under the Endangered Species Act, by Eugene H. Buck, (March 27, 2007), p. 10). For full report, go here.

"Preferred food sources such as some ice seal populations may be declining, but data indicate that the bears are adapting to use alternative food sources, including food sources that may be expanding." (Source: Testimony in Alaska to review listing the polar bear as an endangered species, Tina Cunning, Special Assistant to the Commissioner Alaska Department of Fish and Game, to view).
The temperature changes in the Hudson Bay area over the past several hundred years, the area has been subjected to many extreme temperature changes. "Even if the historical data for Hudson Bay is not calibrated relative to modern stations, it should be consistent within its own frame of reference and shows that over the past several hundred years, the Hudson Bay area has been subjected to many extreme temperature changes. If anything, the temperatures for the 20^th Century have been unusually stable, if the historical record is accurate." The chart appears to show that the temperatures in the Hudson Bay for the 20th Century have been unusually stable. " (Source: "The Polar Bears of the Hudson Bay, Miceal O’Ronain, December 29, 2002)