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See essays related to reindeer/caribou herds in the Arctic Report Card - Note: In 2014, the Arctic Report Card got a new look that included Caribou as an Indicator which will be reported every 2-4 years. Therefore this link goes to the table showing Report Card topics by year, which links to the individual essays.

Caribou are a large animal species found in the North American and Eurasian Arctic. The Porcupine Caribou Herd ranges in northwestern North America. The size of the Porcupine Caribou Herd depends on how many calves are born and survive and how many adult animals die during the year. The herd reached a peak in 1989 at 178,000 and then declined until 2001 when numbers were estimated at 123,000 caribou. The last population estimate in 2013 was 197,000 caribou.*

The Porcupine herd did not grow as quickly other North American herds during the last decades of the 20th century. The birth rate during that period was high and managers suspected that the Porcupine herd experienced greater natural adult mortality than other barren ground caribou herds. Biologists believed that the population decline in the 1990s was probably related to weather conditions (high snow accumulations on the wintering grounds and short summers in the early 90s). *

	Estimated herd size of the Porcupine caribou herd size and 95% confidence intervals 1972 to 2013. Confidence intervals are only available for 2010 and 2013 photocensus attempts. Blue dots indicate successful survey attempts. Data source: Porcupine Caribou Management Board; for details, see 2014-2015 report (PDF).

	Porcupine Caribou parturition rate (percent of cows that had given birth or were judged to be pregnant). This information is gathered from radio-collared caribou cows. Data Source: Alaska Dept. of Fish and Game. From http://www.taiga.net/coop/indics/pchbirth.html. 2008		Peary caribou. Photograph from L. David Mech, http://www.pmel.noaa.gov/arctic-zone/gallery_wolf.html

Find more information (references and websites):

• * From http://www.taiga.net/coop/indics/pchpop.html
• Caribou website from US Fish and Wildlife (Alaska)