Panama is mostly spoken of in terms of its canal and its role in connecting two great oceans for navigation.

But the isthmus also connects two continents and thus allows migration of species between North and South America. And when migration time happens, it’s a crucial connection.

But it’s also one that is threatened by rising seawaters, deforestation and the increasing urbanization in Panama City.

The new documentary, Panama’s Animal Highway, airing on the Smithsonian Channel (Wednesday at 8 p.m. ET), shows how important the bottleneck, no more than 30 miles wide, is for a number of species as well as how biologists are working to learn more about the migrations of millions of birds, mammals, and reptiles each year.

The documentary highlights numerous endeavors including the Sea Turtle Conservancy’s efforts to help leatherback sea turtles lay their eggs on what are shrinking beaches. That’s dramatic enough, but there is also an opportunity to affix trackers on them (left) that allows scientists, for the first time, to determine exactly where specific leatherback sea turtles go in the two years between laying eggs (below).

Tagging is also something done to tiny Prothonotary Warblers — tiny trackers the size of paper clips are affixed to wings to help trace their exact paths.

Up to 3 million raptors can pass by Panama on their journey from North America to South America. There can be flocks of Turkey Vultures, Broad-winged Hawks, and Swainson’s Hawks of up to 2 million in one day late in the fall, and scientists at the Smithsonian Tropical Research Institute keep track.

The documentary also shows the painstaking task of trying to affix a tracker to a Turkey Vulture — a process that begins by bringing in a corpse they’ll come in to feed on.

The documentary also spotlights the use of camera traps — motion-activated digital units that work day and night — that spy what the human eye can’t.

In this special, cougars, which have been using Panama as a bridge to South America, are photographed even when they are elusive to biologists’ eyes. Cougars need the forest to operate, but land in Panama is increasingly being cleared for agriculture and development.

One farmer states he doesn’t like cougars and blames them for killing his livestock. But once he sees a picture of the cougar that was on his property, he becomes more in awe of the animal — perhaps enough to try to share the land with them rather than try to eliminate them.

The agricultural fields have made it easier for coyotes to come south and enter Panama in recent decades. Whether they will continue their push into South America, as llamas did, remains to be seen.

There’s enough activity on Panama to supply a whole series on Panama’s Animal Highway. For now, enjoy what they’ve packed into an hour.