(Not So) Scary Things About Peanut Butter

Photograph by Piccolo Namek, made available via Wikimedia Commons under a GNU Free Documentation License.

Back in December, I wrote about using peanut butter, straight from the jar, as a winter food for birds. Someone then asked about the possibility that sugar or preservatives in commercial peanut butter might be harmful to birds. I decided to do some investigating, and this is what I learned:

As far as I have been able to find out without checking the ingredients of every brand, commercial peanut butters contain salt, sometimes sugar, and what are known as stabilizers, which prevent the oil and solids from separating.

You can leave it on the shelf (for a while anyway)

Preservatives are not generally found in peanut butter because peanut butter has such a low moisture content that it does not support the growth of bacteria—at least, that’s what is claimed by leading peanutbutterologists.

That’s why people are able to keep opened peanut butter on the shelf rather than refrigerate it. However, the oils in peanut butter can go rancid, especially in heat. That jar on your shelf will eventually start to smell off if you leave it long enough, and should be thrown out at that point.

A fungus among us?

Peanuts, hence peanut butter, are also susceptible to an Aspergillus mold (A. flavus, to be exact) that produces the potential liver carcinogen called aflatoxin. Both commercial and “natural” peanut butters are equally subject to this problem as Aspergillus occurs naturally on peanuts as well as on a number of other food products. Amounts of aflatoxin in human food are closely regulated in North America, and most authorities seem to agree that risk from aflatoxin in foods in the industrial world is vanishingly low.

That being said, the risk of aflatoxin contamination is apparently lowest when the peanuts are ground soon after picking and immediately placed in an airtight container. As a result, this may be one of those cases (and they do occur) where buying the big supermarket brand is a safe choice. About 5-10 years ago when the Consumers Union in the United States tested various brands of peanut butter for their aflatoxin content, the highest levels were found in peanut butter “ground fresh” in health food stores, whereas the lowest levels were found in the big supermarket brands.

Trans-fat free?

Another possible reason to be afraid of peanut butter is the stabilizers used to keep peanut butter from separating. Generally these are fats of some type; they used to use hydrogenated vegetable oils but these are being phased out. I don’t have information on what’s being used to replace them. However, in the United States at least (and I suspect in Canada as well), peanut butter must be at least 90% peanuts. The quantity of stabilizers of any type to be found in peanut butter is relatively small.

Our friend, the peanut

Peanuts themselves convey quite a few health benefits, incidentally. According to the Wikipedia, they contain high levels of monounsaturated fats and Resveratrol (a phytoalexin also found in the skin of red grapes), various nutrients, and an antioxidant called p-coumaric acid. The American Peanut Council is even touting a study in which peanuts were found to be so nutritional and satiating that they might be used as a method of weight control.

But that's a possible benefit to me, not a bird. When all is said and done, I've concluded that peanut butter is not very scary at all. I certainly have not been able to find any evidence that birds are placed in any danger by consuming the relatively small amounts of sugar, stabilizers, or salt found in commercial peanut butter.

This item originated as a posting to the NSNature e-list.

Where do little birds sleep in winter?

MANY BIRDS DEPART FOR WARMER CLIMATES when winter comes. But the presence of chickadees, finches, and other small birds at winter feeders attests to the fact that quite a few species stick around all winter long. On warmer winter days these birds' layers of feathers and down keep them quite warm, especially when friendly humans help to make sure they are able to meet their calorie needs. But where do they go at night and in harsh weather?

The importance of evergreens

In harsh weather birds seek shelter just as we do. Dense evergreens are often used for this purpose, which is one of many reasons why it's good to include evergreens in your wildlife-friendly garden. Evergreens that are left to grow naturally--not pruned or limbed up--typically provide better shelter. An evergreen that has been very heavily pruned (for example, to form a hedge) may be so dense that birds can't get into it, making it useless as shelter.

The importance of dead trees

Quite a few species of birds hide from storms in holes in dead or dying trees. Chickadees prefer to nest alone in a cavity just large enough to shelter a single bird. But some species, such as finches, will roost in the same cavity in order to share body heat.

Sadly, dead and dying trees are increasingly difficult to find. You may be able to provide an alternative, however, by putting up what's known as a roost box. This is similar to a nest box in that both are attempts to duplicate a cavity in a dead or dying tree. A roost box is designed for winter use, however, whereas a nest box is designed for use in warmer weather.

How a roost box is different from a nest box

As shown in the diagram above, a roost box is designed to hold in heat: There are no ventilation holes in the top of the box, and the entry is down toward the bottom. Typically the box has perches on the inside, allowing one or more birds to sit comfortably.

In contrast, the nest box does have ventilation holes under the roof. There are no perches in the box because the bird doesn't use it for perching: She builds a nest for her eggs down in the bottom of the box. Placing the entry at the top of the box helps to protect the eggs and baby birds from predators. Often the inside front of the box is roughened or ridged to help the young birds climb out of the box when it's time to leave.

How roost boxes are similar to nest boxes

Neither a roost box nor a nest box should have a perch on the outside. The birds don't need one, and putting a perch on the outside of the box just gives predators something to stand on. Both should have drainage holes in the bottom. Both should have a door that can be opened for cleaning. The exact dimensions of the box will vary depending on the species you're trying to attract; the entry hole should be as small as possible in order to deter predators.

I've found that birds generally won't use nest boxes or roost boxes if there are natural cavities available in the area. (This is a very good reason to protect those dead and dying trees!) However, these are good additions to your property if you live in an area where all the old, dying trees have been cut down.

How to make your own

If you're handy with wood, making roost boxes and nest boxes is an enjoyable project; the boxes are decorative, and there is always at least some chance the birds will use them. Plans for roost boxes are readily available online. Here are a few sites:

• Cornell Laboratory of Ornithology
• Washington Department of Fish and Wildlife Backyard Wildlife Sanctuary Program
• Missouri Department of Conservation
  
  
  
  
  
  

Where have all the (small furry animals) gone?

Hares are among the small animals that remain active all winter. (However, they are not usually seen beating drums.) "Hare and Tabor" is taken from Hone's Everyday Book by William Hone, published 1826. Thanks to FromOldBooks.org for making this image available on the Net. To learn more about William Hone, try this website.

Click here for the previous installment in this series, on insects and spiders.

THE CUTE CHIPMUNK THAT STUFFED HIS CHEEKS at your bird feeders all summer is now literally holed up in its extensive underground burrow. There your little friend has entered a state called dormancy in which breathing, heart rate, and body temperature are slowed. Every two or three weeks the chipmunk comes out of dormancy long enough to attend to personal business and eat the food that it carried back to its burrows in its cheek pouches last summer while it was raiding your feeder. Then it’s back to “sleep” again for the rest of the winter.

Please do not disturb

Dormancy allows many animals to reduce their need for food and stay out of harm’s way during cold winter months. However, it’s a fragile state. Dormant animals are vulnerable to predators, and they can also starve if they run out of fat and food before the winter is over. During the course of the winter, a chipmunk will normally lose almost half of its bodyweight, but if it is disturbed and has to come out of dormancy more frequently than otherwise necessary, it could easily starve. It’s a kindness to keep noisy or disruptive activities out of habitat areas during wintertime.

Hibernation vs. torpor

Dormancy can be shallow or deep. The deep type is sometimes called hibernation or deep hibernation while the shallow type is referred to as torpor or shallow hibernation.

In hibernation, the animal’s body temperature drops and other metabolic activities slow down dramatically. The body temperature of a chipmunk, for instance drops from 37 to 3 degrees Centigrade; its heartbeat drops from 350 to 4 beats per minute.

Among our native small furry animals, bats, and groundhogs (aka woodchucks) are included among the hibernators. Other small furbearers are not deep hibernators but do enter a less intense type of dormancy as a way of conserving resources for short periods. Raccoons and skunks, for instance, will doze for most of the winter in their dens, coming out on warmer days.

Signs in winter

Other small animals remain active all winter, and these are often the ones you see (or see evidence of) around bird feeders. Both grey and red squirrels are active during the day, as you already know. Rabbits and hares and deer mice are also active during the winter but at night, so you will have to look for their footprints in the snow.

Fresh snow is a great place to look for animal tracks, by the way. Learning to tell the difference between tracks of various animals that are active in winter is fun and not terribly difficult. One of my favorite books on this topic is Tracking & the Art of Seeing: How to Read Animal Tracks & Sign by Paul Rezendes. The Peterson Field Guides Animal Tracks guide by Olaus J. Murie is a good resource and the right size to take with you into the woods.