4. Caribou in Alaska and Canada

The movement of the caribou herds in the Arctic is the world’s largest land mammal migration. If you’re close enough and they’re on the move, you can feel the ground shake. However, to see the migration will cost you time and money. The caribou are crossing through remote tundra and taiga near the Arctic Circle, and the locations are hard (generally impossible) to get to without a guide. The migration can range over hundreds and thousands of miles, and due to changes in snowmelt and plant growth, the route shifts from year to year. So your best option for seeing the migration is with an organized group.

Costs for these tours range from $3,000 to $7,000, depending on duration. Trips usually run between May and September and can last between 5 days and 2 weeks. Many involve being taken by plane or boat into the wilderness and dropped off — add camping, hiking, and possibly canoeing or kayaking. Knowing the herds and the ranges will help you determine when and where you might want to see this sight.


In Alaska, there are three major herds: the Western Arctic herd (approx. 348,000 animals), the Porcupine herd (approx. 152,000 animals) and the Central Arctic herd (approx. 23,400 animals).

The Western Arctic herd — the largest — moves through Kobuk Valley National Park and the National Petroleum Reserve Area along Alaska’s North Slope. The herd’s calving grounds are in and around the Utukok Uplands. In May and June, pregnant females and yearlings lead the migration through the Brooks Range Mountains followed by bulls and juveniles. The largest populations can usually be seen in late June.

The herd moves back to its winter range between late August and early October. According to data from the Alaska Department of Fish and Game, important areas of the fall migration, which would likely be where a tour would take you, are the mountains between Salmon and Squirrel Rivers drainages, the Aggie and Ely Rivers, and the coast near Cape Krusenstem.

In spring, the use of the Selawik-Kobuk area is heavy, including movement through “Onion Portage” – a site that has been used by the caribou, and by local tribes to hunt, for thousands of years.

Both the Central Arctic and Porcupine herds use Alaska’s Arctic National Wildlife Refuge (ANWR). While the Western Arctic herd is the state’s largest, the Porcupine herd is perhaps the most famous, due to the intersection of the herd’s calving grounds with a large reserve of natural gas and oil in a region referred to as the “1002” area. It’s around here that the greatest number of this herd can be seen.

In spring, the Porcupine caribou travel around 500 miles to the coastal plains, and they tend to arrive in mid to late May. When mosquitoes hatch in June and July, the caribou gather in huge groups numbering in the tens of thousands and move along the coast, onto ice fields, and to the uplands. By September, the Porcupine herd is heading back south to the wintering areas in the southern Richardson and Ogilvie Mountains in the Yukon Territory.

According to Cathy Curby, Wildlife Interpretive Specialist at ANWR, there are some possibilities of seeing the herds from the road:

Dempster Highway in Canada does pass through the range of the Porcupine herd. A portion of the Central Arctic herd usually winters in southern parts of Arctic Refuge, and some animals summer in the northwest corner of the Refuge. These caribou can sometimes be viewed from the Dalton Highway that travels from Fairbanks to Prudhoe Bay.


The barrenground caribou migration that takes place predominantly in north-central Canada is popular with eco-tourists, photographers, and hunters — this species has the largest antlers relative to their body size. There are 1.2 million barrenground caribou in Canada, split into 8 major herds; the herds may mingle and cross paths during the year, but they are differentiated by the location of their calving grounds, which give the herds their names. In 2004, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) categorized the barrenground caribou as of “special concern.”

Both the Beverly and Bathurst herds of barrenground caribou spend time in the tundra of the Thelon Wildlife Sanctuary, one of the largest protected natural areas in North America and twice the size of Belgium. The Beverly herd is unique since it remains inland, moving to traditional tundra calving grounds including areas near the Pelly and Garry Lakes of Nuavut in spring. By July, the herd moves south to the taiga, and by the fall, they have moved to the forested winter range. In all, the herd can travel over 1,000 miles in a year.

Canada is also home to woodland caribou, the largest subspecies, and these herds don’t go as far north as the barrenground caribou. While some of the woodland caribou herds are stationary, others are migratory. One of those herds is the Leaf River herd, which has around half a million individuals, making it one of the largest herds in Canada.

They have a wide range throughout Québec, and between March and May, the herd moves up to the coastal areas of the Ungava Penisula to calve. By the end of July and throughout August, the herds are moving back south. The George River herd moves in and out of Québec on the way to their calving grounds in Newfoundland and Labrador.

5. Red Crabs on Christmas Island, Australia

christmas island

Photo: NaniP/Shutterstock

At the beginning of the wet season on the Indian Ocean territory of Christmas Island, over 50 million red crabs make a relatively short migration — 2-3 miles — from the forest to the coast for mating.

The migration usually takes place around October and November, though it all depends on the rain. Males head down first, followed by the females. After breeding, the crabs go back to the forest; last year, the return migration was completed near the end of December

Much of the island is protected as Christmas Island National Park. According to the park website:

During peak migration times, sections of roads where crabs cross in high numbers may be closed to vehicles for short periods of time. You can park your vehicle and carefully walk amongst the moving sea of crabs as they relentlessly make their way to and from the shore.

The easiest places to watch the crab migration and the females spawn are at Drumsite, Flying Fish Cove, Ethel Beach and Greta Beach.

The route to the coast goes through human habitat, and they face danger from being crushed by cars when crossing roads. According to the Australian Minister for Sustainability, Environment, Water, Population and Communities, in 2010 “park staff estimate crab mortality at more than 500,000 over the last few months.” The crabs are also threatened by the non-native yellow crazy ant.

6. Wildebeests in Africa

Photo: Dr Ajay Kumar Singh/Shutterstock

Serengeti-Masai Mara

Over one million wildebeests move through Tanzania and Kenya in search of food annually. The herds stretch for miles, dust fills the air, and the grunting of the animals combines with the rumble of pounding hooves that you can feel as much as hear if you’re close enough.

As the migration is dictated by the rains, each year’s is different. All wildebeest calves are born in the rainy season during a short 3-4 week period in late January, February, or early March. The calving takes place in Tanzania along the plains of the southern Serengeti and the Ngorongoro Conservation areas. The calves feed and grow strong; they are preparing for the migration that begins in April and May. It’s a wearying journey and thousands will die along the way.

The herds move by the thousands upon thousands into the central area of Serengeti National Park, following the Mbalageti River through the Western Corridor during June and July. This is where and when the herds have to cross the Grumeti River, though seeing a river crossing is not guaranteed while on a tour or safari. The river crossings can be dangerous for the herds since there are predators in the water, and if the water is high that year, drowning becomes a possibility.

Another chance to see a river crossing is along the Mara River in August and September as the herds move into the Masai Mara National Reserve in Kenya. The herds gather on the plains until November and December, when they head down along eastern parts of the Serengeti back to the calving grounds.

If you can afford it, seeing the sight by plane or hot air balloon is the best way to take in the scale of the migration. A road is being planned to cut through the park, and wildlife biologists and ecologists fear that it would have a negative impact on the migration.

Liuwa Plains

Much less well known than the Serengeti-Masai Mara migration and with far fewer safari and expedition opportunities, 20,000 and 30,000 wildebeests migrate between areas in eastern Angola and western Zambia. With the rainy season starting around November, large herds of wildebeests move from Angola into Liuwa Plain National Park. The herds move back north and west in May and June.

7. Zebras in Africa

Photo: Marius Dobilas/Shutterstock

Approximately 300,000 zebras move along the same route as the wildebeests in Tanzania and Kenya. Another great zebra migration of around 20,000 animals takes place in central and northern Botswana through areas of Makgadikgadi and Nxai Pan National Parks. The animals move with the rain between the grasslands of the Makgadikgadi Salt Pan in the Kalahari Desert and the Boteti River or Okavango Delta.

The dry season, between approximately June and October, finds the zebras along the Boteti River, the only regular source of water. The river had dried up in the past, but in recent years with more abundant rainfall, it’s in better condition and able to support more wildlife, including greater zebra populations. When the rains come, the herds move east to the grasslands and salt pans to eat, mate, and give birth. They journey up to 150 miles, and family groups will stick together as part of the larger herds throughout the migration.

According to an article in Smithsonian magazine on how the zebra population in Botswana has been affected by a 150-mile-long fence built in the Kalahari:

Ten years into the zebra-monitoring project, Bradley and his colleagues can report that the species is thriving. Early indications are that the Makgadikgadi fence does not restrict their migration, which is largely east of the river, and has actually had a positive impact on the park’s wildlife.