Activity Title: 'Cattle Eating Crocs'

Subject Area: Science

Theme: Cattle Stations

Grade Level: 4th - 6th

 

Researching species of crocodiles, students will discover a crocodile’s physical characteristics and habitats. Students will investigate the impact that these reptiles have upon the ecosystem, including their interaction with domestic livestock. Students will create newspaper articles identifying problems and possibilities dealing with the saltwater crocodile population.

Colorado Standard(s) and/or Benchmark(s) addressed in this activity:

Grade	Content Area	Standard	Benchmark
4th - 6th	Science	3-understand the structure of living things	3.1 understand the characteristics of living things and how they interact 3.4 understand how organisms change over time
4th - 6th	Science	1-understand the process of science investigation	1.1 use appropriate tools and measurement devices to gather data

 

National Standard(s) and/or Benchmark(s) addressed in this activity:

Grade	Content Area	Standard	Benchmark
4th - 6th	Science	A-investigate science as an inquiry	A.1-design and conduct a scientific investigation
4th - 6th	Science	C-life science	C.1structure and function in living systems

 

Introduction:

One of the more troublesome aspects of ranching cattle in the Top End region of Australia is the threat posed by crocodiles, especially when cattle drink in rivers inhabited by the ferocious saltwater variety.

The Latin name for the salt-water variety is Crocodylus porosus. One big difference from their freshwater cousins is the stubby snout and considerably stouter frame. Saltwater crocs can also grow up to 7m (21 feet) in length as opposed a maximum of around 3m (9 feet) for the ‘freshies’(fresh water crocodiles) and are quite capable of attacking and eating humans, whereas ‘freshies’ won’t pose a threat unless seriously provoked.

Being a reptile, crocodiles are ‘cold-blooded’ relying upon the heat of the sun for their body warmth. This is why you can very often see them basking on riverbanks in the daytime. If they get too hot, they can slip into the water to cool off. They do not have any of the sophisticated body temperature regulation systems that mammals have for example. During the dry season (March-Oct), many crocs are hibernating. Their main time for feeding and activity in general is during the wet season.

They have a keen sense of smell and can be attracted from several miles downstream by a wounded animal. (We were told us how when the centre of the town of Katherine was flooded last year, a 20ft croc was seen heading down the main street in the direction of the butcher’s shop!)

As well as rivers, saltwater crocodiles inhabit coastal estuaries, swamps and may be seen swimming out to sea, but also dwell in billabongs (a large pool of water) and pools well inland, which they reach by river systems during periods of flood and also by limited overland excursions.

In the spring, females will lay 30-80 hard-shelled eggs in a nest created from soil, vegetation and debris located on a riverbank or side of a billabong. She will defend the nest aggressively until such time as the babies hatch, at which point she will carry the hatchlings to the water in her mouth, trying not to swallow any along the way of course!

As with snakes, crocodiles have a ‘bad rap’ with people due to the ferocious ‘monster’ image we have fixed in our psyche and which is reinforced in films and by the media in general. But statistically, one is far more likely to come foul of an automobile accident. In 1986, for example, 2, 873 Australians died in automobile related accidents. Four people died as a result of attacks by crocodiles during the 4-year period between 1982-86.

 

Vocabulary:

• estuaries
• cold-blooded
• inhabited
• hatchlings

 

Materials:

Availability of research materials including:

• computers
• reptile resource books
• encyclopedias
• journals to record data and observations

 

Preparation:

• research saltwater crocodiles’ habitat
• identify key locations of their location on the continent
• identify population density in ‘saltie’ environments
• list other species of animals that cohabitate with the saltwater crocodiles
• investigate a local newspaper for organization of topics, headlines, etc.

Procedure:

 

Analyze and Conclude:

Assessment Rubric:

Advanced proficient 4	Proficient 3	Partially proficient 2	Unsatisfactory 1
Student identifies three issues that concern crocodile management; list suggestions as to how crocs can inhabit populated areas.	Student identifies three issues that concern crocodile management practices	Student identifies two suggestions that facilitate management of crocodile habitats	Student does not recognize that wildlife habitats need to be managed
Student uses all components in the writing of the news article; text is supplemented with pictures	Student addresses the correct format used in newspaper articles	Student uses three of the five components in writing a newspaper article	Student cannot identify the components of a news article
Student article contains (3) valid, documented resources	Student article contains one documented resource	Student states facts in the news article, but doesn’t document the resource	Student writes from experience without proper documentation for support

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