The Question, and Hypothesis

Question: Will the mexican spotted owl's diet composition noticeably  change between the different parts of mating season?

Hypothesis:
We hypothesize a slight change in the Mexican Spotted Owl's diet compositions across the four different stages of the mating season.
Null:
The prey selection will not noticeably vary with the different parts of the mating season.

Response (Dependent) variable: the variation in diet composition (percentages of birds, rodents (wood rats, voles, rabbits), insects, & reptiles)
Explanatory (Independent) variable: The different parts of the mating season (Courtship, Incubation, Nestling, Fledging )

Procedure:  With the data we already have,  we will individually analyze each year by comparing the diet composition in the four different parts of the mating season. This will be done by determining the percentages of what composes the owls' diets within the mating stages.

Courtship: March- mid april
Incubation:15 april-end of may (1 june)

Mating: to bring animals together for breeding purposes
Fledging: to bring up a young bird until it is able to fly
Incubation: the act or process of incubating
Brooding:to sit upon eggs to hatch, as a bird; incubate
Nestling: a young bird not yet old enough to leave the nest

Intorduciton:  Mating season consists of two different parts: Incubation or brooding, which is when the male owl incubates the egg and the female owls sits upon the eggs to hatch. The second part is Fledging, which is raising the fledglings until they are able to fly. Through our research on past examinations of the spotted owls pellet, it was concluded that the main part of the biomass consisted of wood rats and that this will be the same as ours because these samples were taken during the mating season just like ours. This shows that there will be no major change in diet composition through out the mating season. We do believe though, that it may very a little bit since during the owls' mating season it is also mating season for many other animals, making them easier for the owl to catch. And during fledging the chicks can only eat bugs as first as they work their way up to eat bigger animals, which we will see in the biomass.

Mating season break down:
Courtship (male and female hunting, but male showing off to female) - Feb. 15 - April 15
Incubation (Male only hunting)- April 16- May 31
Nestling (male only hunting)- June 1- 30th
Fledging (both hunting)- July 1st- August
September- chicks leaving, adult pellets only

Wikipedia- Kaitlyn

The extent to which various taxa are eaten by spotted owls varies temporally. Both annual ^[73][76] and seasonal variation in the composition of spotted owl diets has been observed. For instance, pocket gophers, voles, insects, and rabbits are hunted more by spotted owls in the summer than in the winter.^[30][73] In coniferous forests of the Sierra National Forest, birds comprised 12.9% of the California spotted owl's diet during the breeding season but only 4.6% during the nonbreeding season.^[74]

Food habits of Mexican SpottedOwls in Arizona

-Mammals accounted for 73-96% of total prey and 91-99% of prey biomass. Owls consumed prey ranging in mass from beetles (Coleoptera) and moths (Lep- idoptera) (ca 1 g) to adult cottontail rabbits (SyZvilugus spp.; ca 650 g 
-Woodrats, white-footed mice (Peromyscus spp.), and voles (Microtus spp.) accounted for 61-83% of the total prey
 -In general, woodrats and white-footed mice were common in the diet (Z 10% of total prey) in all regions.
 -Dietary composition during the breeding season varied significantly among years (Table 2; x2 = 45.7, df = 12, P < 0.001; N = 4 years and 655 items).
 -I could not compare dietary composition among seasons because most data (79%) were collected during the breeding season. In general, fewer bats and insects were taken during the nonbreeding season (1 September-28 February; Ganey and Balda 1989b) than during the breeding season, whereas the most common mammalian taxa were taken in relatively high numbers in both seasons.
 - side note: wood rats were more abundant in the canyon (These species are most abundant around rock outcrops and cliffs); Voles were more abundant in the forest (species that are more abundant in the grassy understories of forests in the latter regions)
http://www.fs.fed.us/rm/pubs_other/rmrs_1992_ganey_j001.pdf

More interesting facts on spotted owls-kaitlyn

Food and Feeding: Depending on the region and prey availability, the chief prey items include flying squirrels, wood rats, hares, and/or rabbits. Mice and moles also contribute to a diet that is 90% small mammals. There also seems to be a correlation between prey size and breeding success. The mean weight of prey items @ 4.1 oz. were found for successfully breeding owls. A mean weight of 2.8 oz. for prey items were found for owls that were unsuccessful breeding. Other prey include birds and smaller owls, invertebrates, and some reptiles. Breeding: Most nest sites are in natural tree cavities. Additional nest sites include platform nests (mostly constructed by other raptors, wood rats, or squirrels), clusters of mistletoe, and cavities or potholes in cliff or cliff ledges. Most nest sites are used for more than 1 year and are typically 60 - 100 feet high. Usually 2 eggs are laid but as many as 4 are possible. Eggs are laid from March through mid-May and incubation lasts 28 - 32 days. The female will brood the young for an additional 8 - 10 days. The young will leave the nest at 32 - 36 days old onto nearby branches. Since flight feathers, at this point, are not fully developed, the young often fall to the ground but will soon climb up nearby trees to perch. At 40 - 45 days old most owlets can fly short distances. Survival rate for the young Spotted Owls is low. http://owling.com/Spotted_nh.htm Not necessarily on Mexican spotted owls: -They hunt 3 times a day, with the first hunt at around sunset, the second hunt at around midnight, and the third hunt at around sunrise.  -Another mating ritual performed by owls involves the male repeatedly flying from a female’s nest to his own to get her attention. If the female is impressed, she will respond with a unique mating call similar to that of chicks begging for food. The male responds to this call by bringing a freshly caught animal as an offering to the female. The acceptance of this offering often leads to copulation.  - Barn Owls raise multiple broods in a single year if there is an abundance of prey -When prey is scarce, however, it can lead to the older chicks cannibalizing the younger ones.  -Many species provide insects to their young in the early stages and whole rodents once the chicks become large enough. -Spotted Owls rip off the heads of their prey so that digestion and owl pellet production are easier for the chicks. -During the incubation process, female owls rarely leave the nest except to defecate and get water. http://www.carolina.com/category/teacher+resources/owl+resources/reproduction.do

Study Territories

•Both Arizona and Utah study areas have multiple owl territories.

•In Arizona, the territories were:  Spud rock, Helen’s Dome, Italian Spring, Reef rock, and Rincon Peak.

•In Utah, territories were studied in four national parks:  Capitol Reef, Canyonlands, Manti La Sal, and Zion. 

Variables

Independent: The months/ seasons
Dependent: The type or amount of food they ate

Owl's life history

Most owlets (baby owls) leave the nest in June, about 35 days after hatching. Owlets are unable to fly very well when they first leave the nest, and their parents continue to feed them until they become fully independent, usually by October.


http://www.tpwd.state.tx.us/huntwild/wild/species/mexowl/

Info on reproduction

Reproduction
Mating Season: Mid February to March.
Gestation: Around 2 months.
Clutch size: 2-4 eggs.
Most nest sites are natural tree cavities, although Mexican spotted owls also use caves, potholes in cliff ledges and stick nests built by other birds. The young leave the nest at 32-36 days old to perch on surrounding branches, and can fly short distances at 40-45 days. Three weeks after leaving the nest, the young can use their talons to hold and tear prey on their own. Survival rate for the young is low.


Source: http://www.defenders.org/wildlife_and_habitat/wildlife/spotted_owl,_mexican.php

Questions by kaitlyn

(1) does the Mexican spotted owls' diet consist mainly of mammals even in the terrain of the canyon? (2) if a fire has occurred in the area home to the Mexican spotted owl, will it's diet noticeably change?

The blog has been created! time to start brain storming