Principles of Reserve Design

It is generally acknowledges that one of the very best way to protect biodiversity is by setting aside areas of land in reserves and allowing natural processes to proceed largely uninterrupted. These reserves can be in a variety of forms including national parks, protected watershed, or on private property when the owner has agreed to set aside land for conservation easements.  But when the time comes to decide what land should be protected, how much, and in what arrangements, different variables need to be taken into account. Here are some guidelines that are often considered when setting aside land for conservation.

1. It is generally better protect a complete ecosystem. If a whole watershed can be protected, that would be better than if part of the watershed was outside the reserve.

2. Larger reserves are generally better than small one. Large reserves are more likely to have many habitat types and hold larger populations of the species in those habitats. this means that if the choice is to set a side a small area off by itself or add to an already existing reserve, the existing reserve should be expanded.

3. Having a reserve that is unfragmented is better than having one that is fragmented. The fewer roads, power lines, etc. that pass through a reserve the more continuous the habitat will be and so have fewer edge effects.

4. Having more reserves is better than having few reserves.

5. Connecting reserves with corridors is better than having reserves that are isolated from one another. Corridors will be different for different species, for example Black Bears seem to like to use tunnels to get under a road, but Grizzly Bears prefer bridges over the road.

6. In the absents of corridors that connect reserves, creation of stepping-stone reserves can have similar effects. Stepping-stone reserves are smaller reserves that lie between larger reserves. These serve to reduce the total dispersal distance that organisms have to travel to find suitable habitat.

7. Protecting an area with many diverse habitats is generally better than protecting areas that have fewer habitats.

8. A reserve that has a more uniform shape will have fewer edge effects and more undisturbed interior area as compared to a reserve that is long and thin or irregular in shape.

9. Generally speaking, having a variety of large and small reserves in an area is better than having reserves that are all the same size.

10. Managing the reserves in an area jointly is better than managing each one individually. This allows for more specialized and targeted management and better biodiversity protection region-wide.

11. Allowing humans to enter and utilize some of a reserve while protecting a core area is better than excluding humans altogether. While counter-intuitive, if humans are allowed to visit parts of a reserve they are much more likely to support the continued protection of that reserve from future development. If humans are excluded completely, they tend to not realize how important a reserve is.

Now, of course these guidelines are subject to the real world. If there is only one areas of land that has been put up for sale, and the choice is to protect it, or protect nothing, then it is probably better to protect that land even if it is small and isolated from other reserves. But, when choices are available, these guidelines help to create areas that most effectively protect biodiversity.

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Carpenter Bees (Xylocopa)

I have recently been really enjoying watching the Valley Carpenter Bees (Xylocopa varipunctata) around our place in West Sacramento. These bees are the largest species of bee in California, and they are not messing around. They are huge! The females, which are completely black and very dramatic looking, can get up to just over an inch long, and the males, which are yellow with green eyes, are only slightly smaller!

Carpenter Bees are in the genus Xylocopa, the large carpenter bees. There are about 500 species in this genus, worldwide. Five of these species are found in North America and three of them are found in California. Xylocopa comes from the Greek word xylokopos which means ‘wood-cutter,’ a reference to the nesting behavior of these species. The Valley Carpenter Bee is named after the California Central Valley where it is found.

Carpenter Bees have some pretty fascinating behaviors. Generally, they are solitary bees. The females make their nests by boring holes in wood, usually the undersides of branches or beams. They carve their nests by rasping their mandibles against the surface of the wood and vibrating their wings. The holes they bore are not very deep, and so structural damage in not really a concern. However, they are not strictly solitary. Mothers and daughters, or sisters, will sometimes share the same nest. Sometimes they will even divide labor by having one female primarily guard the nest and the other primarily searching for food. Even unrelated females are often quite gregarious, and will often be found nesting in the same general area.

The males generally adopt one of two mating behaviors, and it is easy to tell which species use which strategy by the size of their eyes. Males of some species have very small eyes. These males release large amounts of pheromones that the females use to locate the male. The males of other species have very large eyes. These males search for nest holes of females, and hover outside them waiting for the females to fly by as they are coming or going, and then follow them and try to mate. The male Valley Carpenter Bees that I have been seeing have very large green eyes, so they must use the search and follow strategy.

As with so many other bee species, Valley Carpenter Bees pollinate many flowers, but sometimes they get a bit greedy. If they find a flower that is too deep for them to reach the nectar from the inside of the flower, and so pollinate it in the process, they sometimes use their strong mandibles to slit the side of the flower near the base of the petals and steal the nectar!

If you get to see a Valley Carpenter Bee, they may approach you. Don’t be alarmed. These bees often approach other animals, but both sexes are very docile and the males don’t have stingers at all. So enjoy the visit with these magnificent creatures!

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ABirdingNaturalist Turns 2

Two years ago, today, I published my first blog post on ABirdingNaturalist! In those two years, I have published 111 additional posts and my blog has attracted 4,270 views, been read by people in 67 different countries, and now has 26 followers.

All in all, I a very happy with my blogging experience. It has helped me to clarify my own views and more clearly express them to others. I think this blog has provided useful information to at least a couple of other people which is wonderful as well. But I have a question for you, dear reader. How do I make this blog even more useful? How do I attract more reader? Are there subjects that I have not covered that I should, or ideas that have been included but that should be covered more intensely? Is my blog too scientifically focused? Not scientific enough?

In short, what are the reasons that you read my blog?

Thank you for any thoughts you share, and here is to another year!

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