The road and vehicle as blind is the gold standard. There are some but few trails, and my take would be you'd be less successful than on the road in a car/blind. The wildlife is somewhat accustomed to cars. On trails, unless it is in the open (not a lot of that) you'd not see animals that were there. And there are actually very few trails. One in particular (near middle of the figure 8) has a trail that is good for the smaller birds migrating through. The larger animals you might hear, but not likely see, although they for sure would see you...that includes the resident mountain lion. I've never seen one, few have, but I understand that they are around.

There are lots of quail, especially right at the entrance to the refuge. The pelicans are unusual. I've seen them once or twice at Bosque, but more often at other places (Bitter Lake, or Elephant Butte). And finally, yes! I am very aware and very grateful for this place and my fortunate proximity!!

Jerry, this particular refuge is one of several in a chain that runs along the Red River. Some of them allow hunting but this one, the Headquarters, doesn't. I honestly think the deer know it, too. I'm not shooting from a stand or blind or any other type of concealment. I'm standing in the open on top if the very levee that they're crossing. They'll stop and check me out but, as long as I'm reasonably still, they pretty much ignore me. With the Rut starting, though, I'll have to me more cautious. The bucks can become pretty aggressive if they think you're trying to "horn in" on their ladies. lol.

I owned the EF 100-400mm zoom first, and was very disappointed with its performance. I might have purchased a bad copy. I could never get a sharp image, and its a very heavy lens with its zoom and IS motor. I returned it twice to the factory for adjustment, and it came back worse not better. I then purchased the Sigma 150-500mm, and it was an improvement. I got some good shots, but still soft IMO. It took a lot of post edit to get really acceptable results. I sold both lenses and purchased the 400mm f/5.6L prime lens. Its not the fastest lens in the world at f/5.6, but it is light weight, and absolutely 'Tack Sharp.' I don't need IS because I'm shooting at fast shutter speeds (1/1000s to 1/2500s) most of the time on my 5D Mk2. The results are stellar. A 1.4x or 2x tele-converter negates the AF, and my eyes are too tired and slow to manually focus birds in flight. But the image quality is such that I can tightly crop my shots and still maintain extreme detail in the image. And the price is right, very inexpensive for a L-lens. I shoot handheld and my shots are rarely blurred. It is at its 'best' wide open at f/5.6, and I just bump my ISO if I need a faster shutter speed. With the 5D Mk2 I can shoot at ISO's up to 3200 with very little noise. On my backup shooter 40D I can shoot at ISO 800, and in a pinch ISO 1600. It is an amazing lens IMHO. There are rumors that it might be upgraded soon with IS, and then it will be heavier and the price will skyrocket. This lens has my highest recommendation. It won't disappoint. One final thought, with my 100-400mm and 150-500mm zoom lenses I was always shooting at the extreme FL anyway, so the prime is not a disadvantage in my book. Many wildlife photographers claim it is the 'best' birds in flight lens ever made, and I wouldn't disagree with that statement. An even less expensive alternative is the Tamron SP 70-300mm f/4.0-5.6 Di VC USD lens at $400. It doesn't have quite the reach, or build quality of the 400mm prime, but the IQ is amazing for a lens in that price range. I just sold my Tamron (reluctantly), but it was redundant with me having the 400mm. I would strongly recommend two (affordable) Canon lenses for wildlife photography: The Canon EF 400mm f/5.6L prime lens first; the Canon EF 70-200mm f/4L non-IS zoom lens second. If I had the money (which I don't) I would also consider the the EF 500mm f/4L prime (but is big, heavy and very expensive ... and I travel a lot). Hope this helps. Steve