commonmoorhen

How fast do the tiny toads grow?

The Question: I work at a farm in northeast Pennsylvania. I read your article about toadlets. I have been enjoying seeing hundreds of these mini toads as I garden. Mine are still only about an inch long. How long does it take for them to reach full size?

Submitted by: Victoria, Pennsylvania, USA

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The Short Answer: Victoria, glad to hear you are enjoying the toads. There are so many tiny toads all over my yard right now that I worry about inadvertently stepping on them. In northeastern Pennsylvania where you live, there are two toad species, the American toad (Anaxyrus americanus – formerly Bufo americanus) and the very similar Fowler’s toad (Anaxyrus fowleri – formerly Bufo fowleri). The easiest way to tell the two species apart is to flip them over and look at their bellies. If it has dark speckles, it’s probably an American toad and if not, it’s probably a Fowler’s toad.

toad-growth-chartBoth species start out as tiny toadlets, about 1 cm (3/8 inch) long. They grow rapidly in the first year and then slow down dramatically. By their second birthday, they are pretty close to full grown. Males generally begin to breed in their second year, females in their third. This chart is based on data for the American toad from Frogs of the U.S. and Canada by C. Kenneth Dodd. The book lists the size range of adult American toads as 5-9 cm (2-3.5 in.). The largest American toad on record was a whopping 15.5 cm (6.1 in.). Fowler’s toads are somewhat smaller at 4.5-8.2 cm (1.7-3.2 in.), with a record size of 9.2 cm (3.6 in.).

If your toadlets are already about an inch (2.5 cm), then they must have been early hatchers this year that have done very well eating small insects around your garden. Toads are pretty voracious insect eaters. One study estimated that an adult American toad could eat nearly 10,000 insects a year!

Sources: Dodd, C. (2013). Frogs of the United States and Canada. Baltimore: Johns Hopkins University Press.

Cite this article as: Pelletier, TC. (July 22, 2015). How fast do the tiny toads grow? Retrieved from http://askanaturalist.com/tiny-toad-growth/ on August 2, 2015.
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What to do about this window dove nest?

sam's-doveQuestion #1: This bird made a nest next to my kitchen window. What kind of bird is this?

Submitted by: Samantha, New York City, New York USA

Question #2: A pair of mourning doves have made their nest on the outside windowsill of my home office on the 6th floor of an apartment building. At least one and possibly two fledglings are in the nest and are already trying their wings. I don’t want to harm the birds, but I want to remove the nest as soon as possible because it has infused my office with a barnyard smell. I have read that these birds can raise multiple broods in a season. Is there a time window for me to remove the nest and install a block to prevent their return?

Submitted by: Ron, New York City, New York USA

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The Short Answer: These two reports of mourning doves (Zenaida macroura) nesting on window sills in New York City came within a week or so of each other. In one case, Sam and her small children were thrilled to have a bird nest so easily visible outside their window. In the other case, Ron was a little less happy, because the birds were nested right below his air conditioner, which was pulling in bird nest smell. Still, he was willing to wait till the dove chicks were free of the nest to remove it.

More Information: Like most species of the family Columbidae, mourning doves lay two eggs. They are remarkably flexible about where they will build their nest, sometimes choosing a low bush, and other times nesting 80 meters (260 feet) up in a tree. They’ll also nest on buildings, window ledges and even on the ground.

mourning-dove-chicksParents share incubation of the eggs, which hatch in 14-15 days. They also share feeding of the chicks with regurgitated “crop milk,” a liquid made from partially digested seeds. As the days go on, parents increasingly mix in seeds. The chicks are ready to leave the nest in about two weeks and after their first flight, and once they fledge they may return to the nest for a day or two, and then begin roosting in trees at night. For another two to four weeks the male parent will feed them until they are independent. Meanwhile, the female may begin laying new eggs.

Pairs can raise as many as six clutches in a single year, so Ron’s concern about his doves renesting under his air conditioner is a valid one. The U.S. Migratory Bird Treaty Act makes it illegal to tamper or move the nest of a native bird while it has eggs or chicks, however. So Ron’s best bet for a humane and legal solution is to watch for the baby birds to leave and then wait a day or two and remove the nest, hopefully before the female begins laying a whole new clutch.

Pigeon and doves: As I mentioned above, the family Columbidae includes doves and pigeons. In fact, there is no difference between the two from a taxonomic standpoint. Some members of the Columbidae are called doves and others are called pigeons, but that’s more about traditional names than anything scientific. In fact, our familiar city “pigeon” is also called both a “rock dove” and a “rock pigeon” (Columba livia).

Sources:

Otis, David L., John H. Schulz, David Miller, R. E. Mirarchi and T. S. Baskett. 2008. Mourning Dove (Zenaida macroura), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/117.

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What are these jelly blobs on my car?

gel blob triciaThe Question: I found these on my car in the driveway. What are they?

Submitted by: Tricia, suburbs of Buffalo, New York, USA

gel blob susanThe Question: There were numerous gel filled discs all over my car after a heavy rain. They were clear with tiny yellow specks towards the middle of the blob. What are they?

Submitted by: Susan, suburbs of Buffalo, New York, USA

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The Short Answer: Interesting that I received these two questions within a week of each other, both from the Buffalo, New York area. I’m pretty sure the same, or very similar, insects laid these egg masses on Tricia’s and Susan’s cars. I sent the photos to Dr. Gabor Horvath and Dr. Gyorgy Kriska, researchers at the Eötvös University in Budapest, Hungary who have studied why insects sometimes lay their eggs in the wrong place. Based on the photos, Dr. Horvath and Kriska suggested that these are egg masses laid by caddisflies in the family Limnephilidae. Most species in this large family lay their eggs on leaves overhanging water. When the eggs hatch, the caddisfly larvae drop into the water, where they develop in a fairly standard caddisfly way (see this caddisfly article). They glue together a house, which protects them as they feed on detritus. Eventually, they metamorphose into adults, mate, lay eggs on leaves and start the cycle again.

So why did they lay these eggs on cars, instead of on leaves? How does an insect, with a tiny brain, figure out where to lay its eggs in the first place?

It’s not that a caddisfly female thinks about where to lay. Her brain is coded with a recipe or algorithm for where to lay. For example, the instructions might say, fly till you find yourself over water. Then fly up until you come to a horizontal object. Lay your eggs there. I’m oversimplifying it, but the process is probably something like that. And for many insects, especially those whose eggs and larvae need to be associated with water, automobiles cause confusion. That’s what probably happened in both these cases.

More Information:
Dr. Horvath and Dr. Kriska study insect “mistakes” in order to gain insights into how the vision of insects and other animals works. In the case of insects that lay eggs on cars, the answer seems to be related to polarized light. Light that enters our atmosphere is non-polarized, which means that the light waves are oriented in all directions equally. When light bounces off a horizontal surface, such as the surface of a pond or lake, however, the reflected light is mostly oriented in a single direction. We call that polarized light.

In the natural world, the most common sources of horizontally polarized light are the surface of a body of water, or the surface of leaves. Many insects have evolved to detect that polarized light as an indication of a good place to lay eggs. It’s how they know they are flying above water or leaves and not above dirt. It appears, for example, that Limnephilidae caddisflies use polarized light as one of the signals that suggest a good place to lay their eggs on leaves over water.

Unfortunately, for those caddisflies and other insects that rely on polarized light as an indicator of where to lay eggs, reflective man-made horizontal surfaces, like the dark-colored hood or roof of a car, or even asphalt road surfaces can also reflect light in a way that polarizes it. This can lead to insects laying their eggs on top of cars, which is what Dr. Horvath believes happened in this case.

Thanks: Thanks to Charley Eiseman, co-author of Tracks & Sign of Insects & Other Invertebrates for confirmation that these might be insect eggs, and to Dr. Horvath and Dr. Kriska for their help in suggesting what kind of insect might have laid them and why.

Polarized Light: If you are curious about how the polarization of light works, you might find this video helpful: https://www.youtube.com/watch?v=gP751qpm4n4

Cite this article as: Pelletier, TC. (July 17, 2015). What are these jelly blobs on my car? Retrieved from http://askanaturalist.com/jelly-blobs-on-my-car/ on August 2, 2015.

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Move the tadpoles?

The Question: We have a very old hot tub that hasn’t been used for years and the cover has collected a good amount of water from rain and now looks almost like a tiny pond! We recently we have discovered that it is filled with tadpoles! My dad thinks it is a from a tree frog because he has heard them. Should we move them to a nearby water source? Or just leave them alone?

Submitted by: Patrice, Connecticut, USA

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GrayTreeFrog2010

gray tree frog

The Short Answer: Patrice, gray tree frog (Hyla versicolor) is probably a good guess because they are known to lay eggs in everything from ponds to puddles. Trent University in Ontario has a nice chart that compares some of the common North American tadpoles. You’ll see that gray tree frog tadpoles have red or orange on the tail. Tadpoles of some other species in the genus Hyla also have red on the tail, but the gray tree frog is the only frog in that genus found in Connecticut. So if you see red or orange on the tail, it’s a good bet your tadpoles are gray tree frog babies.

Unless you think the water will dry up, I would just leave them. They’ll feed on algae and other stuff growing in the water and they’ll prey on small creatures like mosquito larvae. Moving them is risky. One benefit of breeding in puddles and other temporary bodies of water is a lack of fish, turtles and most predatory aquatic insect larvae that eat tadpoles. You might move them somewhere where there are predators that will eat them. Or you might move them to a place where they won’t find the right kind of food. The best bet might be to trust that the gray tree frog(s) chose your hot tub pond for a reason, and hope for the best.

If you really want to help your tadpoles, the best thing would be to make sure the puddle doesn’t dry up. That would be sure death for them. So add water if the puddle gets low, but make sure you’re not adding chlorinated water straight from your tap. That might kill them. You could fill a couple of buckets with water in advance, and let them sit for several days. Any chlorine will evaporate and algae will begin to grow. If you later add the contents of the bucket to the tadpole puddle, it will give them water and food at the same time.

You could also try supplementing their food supply with scrunched up tropical fish food if you happen to have some. But don’t overdo it. If you overfeed, the uneaten food will release ammonia and nitrites, which might kill the tadpoles.

It takes about six to eight weeks for gray tree frog tadpoles to metamorphose into adults. Let us know how it goes. Good luck!

Cite this article as: Pelletier, TC. (July 14, 2015). Move the tadpoles? Retrieved from http://askanaturalist.com/move-the-tadpoles/ on August 2, 2015.
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Are these orange ants or spiders?

orange insects-  smallerThe Question: These bright orange insects were all over my deck. I have never seen anything like them. Are they ants or spiders?

Submitted by: Roxanne, Pennsylvania, USA

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The Short Answer: Roxanne, these are neither ants nor spiders, they are the nymphs of an assassin bug, probably the wheel bug (Arilus cristatus). The assassin bugs (Reduviidae) are a family of “true bugs.” To scientists, the “true bugs” are the members of the insect order Hemiptera. The identifying trait of “true bugs” is the proboscis (also called a rostrum), a long tube through which the insect feeds.

Assassin bugs earned that name because most of the 7,000 or so species found around the world are ambush hunters, meaning they either lie in wait or try to sneak up on insects and other arthropods and then pounce at the last second. They kill their prey by piercing it with their proboscis, injecting a paralyzing venom and then sucking out the insides.

If assassin bugs were bigger, they’d make pretty good models for science fiction monsters.

Most species go for relatively undefended prey such as caterpillars, but some species will battle spiders, centipedes and even scorpions. Others specialize in one type of prey, such as millipedes. Assassin bugs will bite people (pierce, really), and although the bite is not generally dangerous, some people report that it’s more painful than a bee sting. If you can avoid picking them up and getting bitten, however, most gardeners are happy to find a newly hatched tribe of assassin bugs such as the ones you have, because assassin bugs, from the moment they hatch, are predators of other insects that we tend not to want, such as destructive caterpillars.

Newly hatched nymphs such as these, by the way, sometimes hunt in a pile-on way. If one of them finds a large prey item and pierces it, the other nearby nymphs will join in killing and draining the hapless victim.

wheel bugIt’s tough to tell from a photo, but if these are in fact wheel bug nymphs, they are destined to become a fairly large adult (2-3 cm, about an inch). They will have a characteristic notched “wheel” on the top of their thorax. The purpose of the wheel is not completely understood. It may have a function in the noises males make to attract females.

What’s With the Crazy Orange Color: The nymphs of many species of assassin bugs sport bright orange or red coloration. Why would a tiny insect want to be so brightly colored? Wouldn’t that make it easy prey for birds and other insect eaters?

Bright coloration among animals can evolve as a warning to predators. This is called aposematic coloration. Most people are familiar with this phenomenon in monarch butterflies or any of the many poison dart frogs of Central America. In the case of the assassin bug nymphs, it may serve as a warning to birds and others that “If you try to eat me, you will be sorry. I will give you a very painful bite.” It’s also possible that they taste bad, due to the same venom they use to paralyze prey.

The evolution of aposematic coloration relies on three things: a predator deterrent, kin selection and learning by predators.

Imagine that a genetic mutation arises that leads to a single wheel bug nymph being bright orange in coloration. Now imagine that a local bird predator sees that boldly colored nymph from far away, zeroes in on it and gobbles it. The bird may decide “Eww that tastes awful!” and be deterred from ever eating an orange bug again. The nymph, however, is already eaten, and the mutation for orange coloration will disappear with it.

But what if the mutation occurs earlier in the egg or sperm formation process so that the entire brood of nymphs end up orange colored. Now imagine that the local bird predator eats the first brightly colored nymph it sees, says “Eww!” and swears off orange colored insects forever. The nymph is probably still dead, but its death now offers extraordinary protection for all its siblings … all of whom are carrying the genetic mutation for bright orange coloration. Given that kind of situation, the orange coloration is likely to become very common since orange colored nymphs are now more likely to survive to adulthood than nymphs that are not orange colored.

This kind of adaptation, where the genetic traits of one individual benefit its close relatives, is called “kin selection.”

The same process could take place if the nymphs are surprisingly painful instead of tasting bad. Imagine that a bird tries to eat a nymph, but gets pierced inside its mouth in the process. It’s not very likely to go for those bright orange nymphs next time … unless it’s really, really hungry.

I said the evolution of aposematic coloration also requires learning on the part of the predators.  That’s because if the local predator eats an orange nymph and says “Eww!” but the next time it sees an orange nymph it doesn’t remember that the previous one tasted bad, it will eat that one, too, and the siblings of bad-tasting orange nymphs won’t gain protection. Vertebrate predators like birds are certainly able to learn, and probably some invertebrate predators have learning ability as well.

So, we have a nymph that probably has a nasty taste and definitely has a nasty bite. We have large brood sizes that allow “kin selection.” And we have predators that can learn to avoid orange nymphs.

The result is startlingly day-glo orange nymphs.

assassinsThis process should work just as well for adult assassin bugs, and sure enough, the adults of many species are also brightly colored and patterned, usually featuring bright red or orange. In other species, including the wheel bug, however, the bright coloration disappears by the time they are adults. Adult wheel bugs are a camouflaged grey color. It may be that for some adult assassin bugs like the wheel bug, camouflage that helps it catch prey is more important than warning coloration that helps it avoid predators.

For Your Viewing Pleasure: Here are a couple of videos that can help you gain an appreciation for assassin bugs:

This video is annoyingly overhyped with bizarre fake sound effects, but it does show a nice sequence of an assassin bug hunting a caterpillar: https://www.youtube.com/watch?v=i0NYdQ3gEwo

This one shows assassin bugs hunting different insects: https://www.youtube.com/watch?v=AE43rai4Lho

This one shows eggs and nymphs and has some good information: https://www.youtube.com/watch?v=1qBkEY6QFb4

Thanks:  Thanks to bugguide.net for confirming the ID of these nymphs.

Sources:

C. Weirauch et al. (2014). An illustrated identification key to assassin bug subfamilies and tribes. Canadian Journal of Arthropod Identification. No. 26.

Cite this article as: Pelletier, TC. (July 11, 2015). Are these orange ants or spiders? Retrieved from http://askanaturalist.com/bright-orange-insects/ on August 2, 2015.

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