Intelligence is difficult to measure in humans, let alone animals. Finding a single measure of intelligence for different species is extremely difficult. The ability to use tools is one well-respected measure. Another good measure is problem-solving ability. Flexibility is key, particularly the ability to apply general rules in solving new problems and adapting to changing circumstances. Lately, saltwater crocodiles Crocodylus porosus have attacked an average of one person every month in this small island nation of 1.
Many Timorese, especially the poor, rely on the waterways for their daily activities. Crocodiles are expert at targeting people bathing, collecting drinking water, washing clothes, or fishing in small boats. The rate of attacks has jumped from fewer than one per year in to more than a dozen annually. Many Timorese believe that the rise in attacks is due to crocs swimming over from Australia in search of food. But DNA results seem to indicate that it is the relatively low numbers of indigenous saltwater crocodiles that are responsible, not foreign crocs.
A similar story is unfolding in the Gujarat district of India, with a population of over 3. The area is home to hundreds of mugger crocodiles Crocodylus palustris and their numbers are rising.
With the jump in crocodile numbers, attacks on humans have also increased in the past two decades. From to there 60 attacks reported in the state—an average of one attack per year. But in alone, the number of attacks was As in Timor, people use the water bodies for fishing and washing, as well as for the potty, making them vulnerable to crocodile attacks. Croc attacks appear to be on the rise throughout south-east Asia and Africa.
Both crocodilian populations and human populations are increasing, so the potential for conflict is increasing. In addition to human population growth and crocodilian population growth, there are other variables such as habitat loss and increased water use.
These trends indicate the flexibility of crocodiles in adapting to their changing environment. Like all top predators, they have an important role to play in maintaining balanced ecosystems by controlling smaller animals that could easily reach pest levels if numbers went unchecked. Unfortunately, many of the villagers who depend on access to local waters are paying the price as these skillful hunters take advantage of new opportunities. The more humans you have living in crocodile country, the more likely you are going to have these negative interactions with crocodiles.
I love to find stories of creatures doing fascinating things. During bird nesting season, loose sticks and branches can become a sought-after commodity. Herons and egrets build large nests and are always on the lookout for fresh supplies. Some crocodiles and alligators have learned to strategically place loose sticks on their snouts as lures to bring the unsuspecting birds within reach of their giant crushing jaws.
Vladimir Dinets refers to this as stick-displaying behavior. Did you know that crocodiles have a social life? Crocodile communication is complex and multimodal, which means that the animals use various means of communicating such as visual, chemical, and acoustical signals.
If you thought body language was important for humans, imagine how important it would be living and hunting in water that can be dark and murky. Young crocodiles are especially reliant on communication with their mothers, and communication begins even before they hatch. Hatchlings will call out to one another while still inside their eggs, to help synchronize hatching time. The mother will respond to these calls by opening the nest and helping the newly hatched youngsters out of their shells.
She usually takes them in her mouth to the river or pond to improve their chances of survival. Crocs are known to be hierarchical communicators using a range of visual displays and loud bellows to assert dominance. The large dominant males play an important role in keeping the younger potentially troublesome males in line. The saltwater, or estuarine, crocodile is well-adapted to saline and can spend weeks or months living in brackish or salty sea water. Some species of crocodiles gather in groups to perform performing mating choruses that included infrasonic vibrations—a form of communication that is extremely rare in nature.
The microphones have picked up a curious, deep underwater booming. Researchers are wondering if they might be able to use recordings of certain calls to keep the predators away from populated areas. This is one aspect of crocodilian behaviour that is not very well researched, but it is intriguing. We found that the shape of the frequency modulation is the key parameter eliciting a behavioral reaction from juvenile crocodiles.
Conversely, an altered call that kept the original frequency modulation shape signals noAM, 1H, SLOPE1 in the figure remained as efficient as the original call of the Nile crocodile signal Control in the figure.
Tested animals were highly tolerant to modifications of the acoustic structure of the calls provided sounds keep the frequency slope. This experiment thus shows that juvenile calls of crocodilians share the same acoustic code. This may be problematic if different species live in the same habitat. However, in most cases the biggest species would chase the smallest one from its area, limiting the acoustic confusion between juveniles of different species.
Crocodilians together with birds are the modern representative of archosaurs, a group that also includes the extinct dinosaurs and pterosaurs. In both crocodilians and birds, sound signaling is important during parents-young interactions. The use of acoustic communication in the context of parental care is thus likely to be a shared behavioral feature by all archosaurs, including those of the past.
Spectacled Call : Call of a Spectacled caiman juvenile. Modified Call : Modified call of a Nile crocodile juvenile. This call contains only one harmonics, but keeps the slope of the frequency modulation of the natural call.
Nile juveniles do react to this sound. The comparative study of birds and crocodiles represents one approach to this interesting problem.
One of their shared behavioural features is the use of acoustic communication, especially in the context of parental care. Although considerable data are available for birds, information concerning crocodilians is limited. The aim of this review is to summarize current knowledge about acoustic communication in crocodilians, from sound production to hearing processes, and to stimulate research in this field.
Juvenile crocodilians utter a variety of communication sounds that can be classified into various functional categories: 1 "hatching calls", solicit the parents at hatching and fine-tune hatching synchrony among siblings; 2 "contact calls", thought to maintain cohesion among juveniles; 3 "distress calls", induce parental protection; and 4 "threat and disturbance calls", which perhaps function in defence.
Adult calls can likewise be classified as follows: 1 "bellows", emitted by both sexes and believed to function during courtship and territorial defence; 2 "maternal growls", might maintain cohesion among offspring; and 3 "hisses", may function in defence.
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