A 40 liter REI backpack; Leica 10x42 Ultravid HD-Plus binoculars; Leica 65mm Televid spotting scope with tripod; Leica V-Lux camera; GoPro Hero3 videocamera; 11" MacBook Air laptop; iPhone 4; iPod nano; Surefire Fury LED spotlight; Yalumi LED headlamp; Marmot down jacket; Columbia rain shell; 4 lightweight Mountain Hardwear T-shirts; longsleeve collared bug shirt; one pair of shorts; 2 lightweight pants; 3 pairs Ex-Officio underwear; 4 pairs socks; plain black baseball cap; Oakley sunglasses; 2 kinds of bandanas; silk sleeping bag liner (but no sleeping bag); travel lock; adapters; notebooks; Audubon pins; and various toiletries including malaria pills and Israeli water-purifying tablets. Photo: Noah Strycker

All you really need for a year of international birding is a pair of binoculars, a pair of pants, and a passport, but my packing list is slightly more luxurious than that. I have just one rule: Everything must fit in a carry-on bag. No checked luggage allowed!

The benefits of packing light should be obvious. I skip most airport lines, will save hundreds (thousands?) of dollars on checked-bag fees, don’t worry about things getting lost, and am generally more nimble. I can walk around with all my stuff if necessary; for instance, in northwest Argentina I carried everything on my back while hiking in the mountains for four days. All forms of transportation are way easier without bulky luggage. I wouldn’t do it any other way.

Carry-on has its limitations, though, usually measured in volume. I settled on a 40-liter backpack from REI, which looked big enough on the Internet but appeared somewhat smaller in my living room. It’s not much larger than a kid’s schoolbag, but it helped me make the right choices—I just told myself, “If it doesn’t fit, I don’t need it.”

The result is a pretty svelte travel kit. Compressing your life into 40 liters is an interesting exercise, and it shows your priorities. I’ve done this once before, when I hiked the 2,650-mile Pacific Crest Trail in 2011, and the gear list from that adventure is surprisingly similar to this one. The PCT first taught me that the farther you go, the less you need, a lesson which I’ve carried forward into this big year.

Here, below, are some highlights of my gear list, ordered roughly from heaviest to lightest:

Optics: Definitely the heaviest item in my pack! I managed to fit a Leica 65mm spotting scope with a four-section tripod (folds down smaller) and a pair of Leica 10x42 HD-plus binoculars. No birder should willingly skimp on optics, and these are the crystal-clear eyes of my big year. I also have a Leica V-Lux camera, which is a nice balance between a pocket point-and-shoot (which would be tough for bird photos) and a typical SLR camera (which would be too heavy). As backup I have a tiny GoPro Hero3 (good for videos) and the camera on my phone.

Electronics: Having never been a Mac person, I must admit that the 11” MacBook Air is an ideal travel laptop. It has great battery life and turns on instantly so I can flick it open anywhere (this year I’m working a lot in cars and on planes). I use an iPhone for several things: To keep track of bird sightings (via the BirdLog app which uploads to eBird); check email and make calls (I switched to T-Mobile this year, the only U.S. carrier to include international coverage without roaming fees); and as a reference (before leaving home, I scanned several dozen field guides and put them on my laptop and phone, so I don’t have to carry paper ones).

Clothing: Lightweight pants (2); shorts; synthetic T-shirts (3); insect-proof button-up longsleeve; warm longsleeve; down jacket; thin rain shell; lightweight long underwear (might ditch); undies (3); smartwool socks (3), neck warmer; cotton handkerchief (useful as a towel/cleaner); baseball cap; sunglasses; flip-flops; and tennis shoes. I brought some warmer layers for Antarctica at the beginning of the year and gave them away, and picked up a pair of rubber boots and an umbrella which I will carry through South and Central America.

Other: Israeli water purification tablets (said to be the best); a year’s supply of malaria pills (haven’t needed any yet); silk sleeping bag liner (useful for low-rent rooms without sheets); high intensity LED flashlight (for owling); plastic spoon (very useful!); travel lock (might ditch); and a bottle of Tabasco-flavored jelly beans (for those moments when you just have to spice things up).