Owl Pellet Studies at Altamont and Jefferson Elementary Schools

On Friday, March 25, I visited the Altamont Elementary School and worked with three fourth grade classes. I worked with Ms. DeGennaro, Mrs. Flanagan and Mrs. Vogel’s classes. Here is what we found when we dissected owl pellets.

Ms. DeGennnaro’s class – in 8 pellets dissected we found 20 mice, 1 shrew, 0 moles and 0 birds

Mrs. Flanagans’ class – in 9 pellets we found 24 mice, 1 shrew, 0 moles and 0 birds

Mrs. Vogel’s class – in 8 pellets we found 24 mice, 0 shrews, 0 moles and 0 birds

This is a very small sample to use to determine if my hypothesis (remember I had answered the question, “What is an owl’s favorite foo?” with the hypothesis that mice were the most favored, shrews second most and moles and birds tied for third) was correct. Clearly, mice are the most favored, but before we can say that shrews are the second most favored we have to think about what these numbers mean.

Yes, there were 2 shrews found in the 25 pellets we dissected along with no moles or birds. That may or may not mean that shrews indeed are the second most favored over moles and birds. Our sample size of owl pellets is very small. Because of this we should not be ready to say that shrews are surely the second most favored food. We would want to dissect more pellets to get more evidence. As a matter of fact I did an owl ecology session with 5^th graders at Jefferson Elementary School in Rotterdam today. Here is what we found.

Mrs. Bondi’s class – in 11 pellets dissected we found 32 mice, 0 shrews, 0 moles and 0 birds

Mrs. Walker’s class – in 11 pellets we found 24 mice, 0 shrews, 0 moles and 0 birds

Mrs. West’s class – in 11 pellets we found 29 mice, 7 shrews, 0 moles and 0 birds

Mrs. Fiske’s class – in 9 pellets we found 23 mice, 1 shrew, 0 moles and 0 birds

Mrs. Zanta’s class – in 11 pellets we found 37 mice, 2 shrews, 0 moles and 0 birds

Looking at just the Jefferson Elementary findings we see out of 53 pellets dissected there were 145 mice, 10 shrews and no birds or moles. This confirms what we found at Altamont, mice are the most favored. Now with a larger sample size we can better determine the preference for shrews. With two shrews found by the Altamont students and 10 shrews found by Jefferson students it does appear that shrews are the second favored food. With no moles or birds found at either schools we are still not sure if they are a third favored food. As a matter of fact with no moles or birds found we might presume that they are not eaten at all.

Just as discussed in each class I visited, the more pellets we can dissect the better of an understanding we will have for owl food preference. If we increase our sample size we would get more data that might shed light on the question of what role do moles and birds play in the owl food preference. We can do that by looking at what was found in owl pellets dissections in other schools, including what was found at Altamont and Jefferson Elementary schools in previous years. To do this check out my blog at www.schoolyardnaturalist.blogspot.com to see what the findings at other schools were and then draw conclusions about my hypothesis.

Of course if any student would like to do further studies on their own and dissect more pellets they can get pellets from Pellets,Inc. at www.pelletsinc.com. Naturally if students have more questions they can e-mail me and I would love to help them with their research.

Field Ornithology at Ostrander Elementary School, Wallkill, NY

Here are the results of the spring bird surveys that were done with Mrs. McQuiston, Mrs. Wager, Mrs. Missale and Mrs. Stokes’ 3rd grade classes on Thursday and Friday of last week.

Mrs. McQuiston’s class

Thursday, March 17, 2:00 PM

Temperature – low 50’s

Strong breeze from the west

5 % cirrus cloud cover

Red-tailed Hawk – 2

Ring-billed Gull – 2

Mourning Dove – 3

American Crow – 76

American Robin – 4

Northern Cardinal – 3

Red-winged Blackbird – 8

Common Grackle – 3

House Sparrow – 10

111 birds total among 10 species

Mrs. Wager & Mrs. Missale’s class

Friday, March 18 ,11:40 AM

Temperature – high 50’s

Very strong west wind

99% low cumulus cloud cover

Canada Goose – 315

Red-tailed Hawk – 3 (2 adults, 1 juvenile)

Ring-billed Gull – 1

American Crow – 4

American Robin – 4

European Starling – 4

Red-winged Blackbird – 12

Common Grackle – 7

House Sparrow – 7

360 birds total among 9 species

Mrs. Stokes’ class

Friday, March 18 2:05 PM

Temperature – high 60’s

Very strong west wind

20% cumulus cloud cover

Red-tailed Hawk – 4

Mourning Dove – 3

American Crow – 1

American Robin – 7 Cedar Waxwing – 3

Northern Cardinal – 1

Red-winged Blackbird – 12

Common Grackle – 9

House Sparrow – 10

37 birds total among 9 species

A total of 12 different kinds of birds were observed. Six species were seen by all three groups. The Canada Geese were for the most part in three large groups at very high altitude. These birds were definitely in migration heading north. The large numbers of crows seen on Wednesday with Mrs. McQuiston’s class were likely birds heading back to roost from their daytime feeding areas. These birds streamed past in a loose group over a period of a few minutes. We wondered if we might observe a similar movement on the 17^th. We did not. This was likely due to the high winds that day. The strong westerly winds on the 17^th were about 20 to 30 mph and may have affected how, when and where the crows flew that day on their way from their feeding areas.

A classic way to judge winds speed is the Beaufort Wind Scale developed in 1806 by Sir Francis Beaufort, a British admiral. See link to the right to go to the Wikipedia entry for more information on Beaufort and how to use his scale to measure wind speed.

It would be interesting to observe birds around the school as the season progresses. In a few short weeks many more different kinds of birds will be returning from their winter homes to find nesting areas around the school. At the same time large groups of birds like the Canada Geese and the American Crows will most likely not be seen as this grouping or flocking behavior would not be done during the nesting season. An overall year list of birds would give an idea as to the birds that migrate through to more northerly habitats, return to nest during the warm weather or are resident all year round. Such a list if maintained over a number of years could be used to determine such things as global climate change, habitat change or species change in the environment.

Compare bird observation findings at other schools in my blog. Look through the archived entries to see done at the same schools in different years, on different dates and at different times.

Owl Pellet Study at Ostrander Elementary School

I completed the final owl study class with 2^nd graders at Ostrander Elementary School in Wallkill, NY today. Here are the results of the owl pellet dissections.

Dutka’s class – 8 pellets dissected, prey found – 22 mice, 3 shrew, 0 moles, 1 bird

Lupoli’s class – 8 pellets dissected, prey found – 17 mice, 3 shrew, 1 mole, 1 bird

Nisa’s class – 5 pellets dissected, prey found – 7 mice, 3 shrew, 2 moles, 0 birds

Busse’s class – 8 pellets dissected prey found – 15 mice, 2 shrew, 0 moles, 0 birds

I had presented the following hypothesis to the students in response to the question what is the favorite food of Barn Owls. Mice and other rodents are the most favored food. Shrews, small insectivore mammals are the second favored food. Moles, another small insect and worm eating mammal, and birds, small birds mostly found in barn areas are tied for the third most favored food. What does the data tell us about the hypothesis?

In the 29 pellets dissected there were 77 prey animals found. Of these 77 animals 61 were mice. Mice were definitely the most favored food.

My hypothesis stated that shrews were the second favorite. Is that correct? Of the remaining 16 animals eaten by Barn Owls that produced the pellets we dissected 11 were shrews. What do you think?

Now look at the number of moles and the number of birds eaten, 3 and 2. Though it is not an exact tie, you can’t get any closer to a tie than that. It does seem that moles and birds are tied as the third favorite food.

Finally consider this. There are many other potential prey for the owls, small amphibians, large insects, other small mammals, but it seems from what we found that owls seem to not prey on them. You can research this to find out if Barn Owls might eat other animals. One research source is my blog, www.schoolyardnaturalist.blogspot.com. Check it and see what other data has been collected with owl pellet studies at other schools, including what was found at Ostrander in previous years.

A January Owl Ecology Class

I am late with this post. My apologies to the young ornithologists at the Nazareth Intermediate School in Nazareth, PA. In January I had my annual visit to this school where I did a lesson on Owl Ecology. We talked about the 4 common owls of the Nazareth, PA area, the Eastern Screech-owl (Otus asio), the Great Horned Owl (Bubo virginianus), the Barred Owl (Strix varia) and the Barn Owl (Tyto alba). Our discussion covered the identification, behavior, and habitat needs of these owls. We also talked about how students might do field studies of the owls with the help of their parents or other responsible adults.

We then dissected owl pellets to see what food preferences the Barn Owl has. The pellets we dissected were from western Barn Owls purchased from Pellets,Inc. (see link below to the right). Here is the data we collected.

Thomas/Miller classes 24 pellets, 54 mice, 6 shrews, 2 moles, 1 bird

Kimble/Velekei classes 26 pellets, 52 mice, 4 shrews, 4 moles, 0 birds

Roth/Giemza classes 24 pellets, 57 mice, 6 shrews, 1 moles, 1 bird

Emrick/DeBoer classes 24 pellets, 37 mice, 8 shrews, 5 moles, 1 bird, 1 insect

Genua class 12 pellets, 28 mice, 6 shrews, 3 moles, 1 bird

Reed class 10 pellets, 12 mice, 5 shrews, 1 moles, 0 birds

Rohn/Quinones classes 23 pellets, 45 mice, 4 shrews, 1 mole, 0 birds

Reynolds/McCarron classes 25 pellets, 50 mice, 6 shrews, 3 moles, 2 birds

Analysis

One hundred sixty-eight pellets were dissected by fourteen classes of 4^th graders. A total of 335 mice, 45 shrews, 20 moles and 6 birds were found. In addition to these prey, one pellet included the remains of an insect. These remains appeared to be leg segments from a something like a mole cricket (Gryllotalpidae family). Taken in whole this data indicates that on average Barn Owls eat 2.42 animals per meal (the pellet is a result of a meal – in one night the owls might produce 3 or 4 pellets as they feed, then stop to rest and digest and then go back to feeding throughout the night). This average matches findings with other owl pellet dissections conducted with other schools (see archives for other owl pellet dissection results).

In our discussion before the dissection we had hypothesized that mice would be the favorite food, with shrews second favorite and moles and birds tied for third. It is clear that mice indeed are the most common prey and that shrews are second. It seems though that moles are more often eaten than birds by a factor of three. Look through other owl pellet dissections in the archives of this blog and see if this bears out with the findings in those sessions.

I wonder if the owl ate the insect as a primary prey or if it might have ingested the insect when it ate a mole that had eaten the cricket. Moles feed on underground insects and other invertebrates. It is possible the mole had just eaten the cricket and then was eaten by the owl. Unfortunately I did not take notes as to what else was found in the pellet with the insect parts. If mole remains were found along with the cricket remains that would support the idea that the owl ate a mole that had eaten the cricket. If I ever find insects parts in owl pellets in the future I know that I will be sure to make note of what other prey were found in the same pellet.

The owl food chain affects farmers. Since mice, and these mice are for the most part are field mice (Microtus spp), are the favored prey the owls, eating them affects farm production by reducing the amount of plant crops eaten by the mice. I have a little math exercise I call “Mouse Mathematics” that I will post in the near future that illustrates what this cost savings for a farmer might be. Look for it being posted soon.