Identify the trophic level of the toad.

Outline a method that could be used to estimate the population of rabbits in this environment.

The Simpson diversity index is used to calculate the species richness in an ecosystem.

Define the terms N and n in the formula above.

N =

n =

tertiary consumer / fourth trophic level

capture – mark – release – recapture method;
marked unit area;
apply a paint spot/ear tag/leg ring/radio transmitter to the captured rabbits;
sufficient time must elapse to allow mixing of population to occur;
second capture must be from same marked area;
calculate the Lincoln index / population size
n1=first capture, n2= second capture, n3= number marked in second capture;

N = total number of organisms of all species found;
n = number of individuals of a particular species/per species;

Many were able to correctly identify the trophic level as tertiary consumer. Candidates should not use unexplained symbols when answering questions.

 Very few descriptions of the capture-mark-release-recapture technique were given. Several candidates mentioned the use of 1 m² quadrats. While they do give a marked unit area, they are not suitable for mobile species such as rabbits

Most candidates did not know what the N and n stood for in the formula for the Simpson diversity index.