Greetings from southeastern New Mexico, on the edge of the Permian Basin. Maisie, the birds, and I are well into the ’23/’24 Southwest Peregrination and we’re all having a very nice time. Yesterday was forecast to be very windy – not a good day for flying the birds – so I traveled down to Carlsbad Caverns N.P. to take a walk underground.

First things first. The cave system was gorgeous and HUGE. The entrance was familiar – I’m positive it was the background for the freetailed bat illustration in my childhood Mammals: A guide to familiar American species Golden Guide.The shape? Yes. The scale? Yikes!

From the surface, it’s a 1.25mi/2k hike down switchbacks until you are 750’/245m down at the Big Room. The walk around the Big Room is a similar distance, but flat. A single chamber that takes about an hour to circumnavigate on paved paths. Big.

As I was walking, I couldn’t help but compare Carlsbad to Kartchner Caverns. I visited Kartchner last winter – it’s in southern Arizona and was discovered and opened as a show cave more recently than Carlsbad. There are obvious similarities: humidity, temperature, formations, but they felt different. I’m putting it down to what I’m calling metabolism (I’m sure there’s a real term of art for this). Kartchner has a higher metabolic rate – more dripping, more wet surfaces, more of a feel that things are growing – still on a very long time scale, but… Cave systems are unique – I knew this intellectually, but feeling the difference between 2 pretty similar systems was striking.

The other thing that I’ve been thinking about since yesterday’s hike has been the “island” aspect of cave ecosystems. Kartchner Caverns is in the Sky Island region of southern Arizona – a desert with mountaintop ecological islands. It makes for fantastic hiking and biking – moving through very different kinds of habitats as one climbs. Similarly as one descends below the surface, the parameters change. Temperature and humidity stabilize and light disappears. Something that has adapted to Carlsbad (below the twilight zone) is not going to be able to pull up stakes and migrate to the next cave system along. I’m thinking primarily of microscopic critters – bacteria and pals – but big respect to cave crickets and salamanders and all the other macro beasts, too.

I’ll be back in Sky Island country after the holidays – I plan on going back to Kartchner Caverns (note to self – look at their calendar for cameras-allowed special tours) and will definitely be rolling this stuff around in my head as the squad and I go exploring aboveground.