Lab 4

Part 1: Owl Pellet Dissection

Table 1: Pellet measurements:

       Length: 44.449 mm

       Width:  31.74 mm


Bones found in owl pellet:

Reconstructed rodent skeleton:

Table 2: Kinds and Number of Animals Found in Owl Pellets
	# Rodent	# Moles	#Shrews	#Birds	# Others
Your       Data	1	1	1	0	1

Bar Graph: Animals in Barn Owl pellet

Part 2: Ecological pyramids

Trophic (feeding) Pyramid for a 24-hour Period:

 

Equations for "Trophic Pyramid in a 24-hour Period":   

R = # 2˚ Consumers    

         # 3˚ Consumers  

            4  = 4 Ratio

            1

  # 1˚ Consumers = R (# 2˚ consumers)   

           4 (4)= 16    1˚ Consumers

  # Producers = R (# 1˚ consumers)  

            4 (16)= 64  producers

           

  1.   During the nesting season the young need an enormous amount of food for growth. If the nest contains three young and each of the young eat five mice per night for a month and the two adults eat four per night, how many mice would the parents have to capture in 30 days? 

              a.  690 mice would need to be captured to feed the family for 30 days.

        2.   The pellets are from what owl family?
              a.    Barn Owls

       3.   Environmentalists are concerned about the accumulation of certain poisons in predators. Why do you suppose owls, eagles, swordfish, humans and lions are often the most threatened organisms of a community that are exposed to DDT or mercury?
              a.  The process of biological magnification or substances that are bioaccumulators (toxic substances, e.g. DDT and mercury, that organisms absorb at a rate that is greater than that at which the substance can be processed out of the organism) cause concentrations of exposure to increase with each exposure.  The food that is consumed by the top feeders in a food chain may contain small amounts of toxins however these predators need to eat a lot of these organisms in order to survive which increases their toxic substance intake with every meal.