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Post by Bujang Senang on Mar 4, 2020 13:30:39 GMT 5
From Google Translate: Note that Medem states the GWS and several other shark species are enemies of the adult American crocodile. It's a pretty easy inference to believe that inhabitants observed white sharks attacks on adult crocs, along with probably juveniles. Again, this simply shows the typical shark/croc interaction, the larger animal dominates and may prey on the smaller one. "The only natural enemies of adult crocodiles are the "tiger" (Pantheru onca) and several tiburones, espccially the "white shark" (Car charodon carcharias, Isuridae), which abounds around Isla Fuerte. On May 5, 1955, a 230 cm long one was found at night and already in an advanced state of decomposition, in the bay of the Pto. Limon farmhouse located to the east of this island. His belly was about 30 cm wide. the intestines, part of the flanks and the right hind limb were missing, while the rest of the body, including the cranc, has been left. (CNHM 74923), it was intact. According to the inhabitants, it was quite common for white sharks to attack crocodiles in the sea, between 20 and 200 meters from the coast, and that this reason, they could not migrate to the mainland (8 km) or vice versa." It makes sense, but he also listed other sharks as well as jaguars as "natural enemies of adult crocodiles". It is also possible that Medem just referring to other formidable predators capable of dealing with an adult C. acutus. I think great white shark are more than capable to take both juniviles and adult C. acutus swimming in sea, given the small size of this Crocodylus species in coastal habitats as well as the lack of reasons for migration for the largest dominant crocs. But this is just an anecdote from the locals, described with a small amount of detail... Look how much attention is paid to this anecdotal account in shark-crocs discussions, e.g. in the paper by James Nifong. |
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Post by dinosauria101 on Mar 4, 2020 23:39:18 GMT 5
Apparently, it was somewhat common in the 50's. I've heard GWS are relatively rare there now, probably for a variety of environmental and natural factors. So I doubt it's common now. Haven't GWS been somewhat on the increase worldwide? It may become common again |
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Post by elosha11 on Mar 5, 2020 9:33:50 GMT 5
From Google Translate: Note that Medem states the GWS and several other shark species are enemies of the adult American crocodile. It's a pretty easy inference to believe that inhabitants observed white sharks attacks on adult crocs, along with probably juveniles. Again, this simply shows the typical shark/croc interaction, the larger animal dominates and may prey on the smaller one. "The only natural enemies of adult crocodiles are the "tiger" (Pantheru onca) and several tiburones, espccially the "white shark" (Car charodon carcharias, Isuridae), which abounds around Isla Fuerte. On May 5, 1955, a 230 cm long one was found at night and already in an advanced state of decomposition, in the bay of the Pto. Limon farmhouse located to the east of this island. His belly was about 30 cm wide. the intestines, part of the flanks and the right hind limb were missing, while the rest of the body, including the cranc, has been left. (CNHM 74923), it was intact. According to the inhabitants, it was quite common for white sharks to attack crocodiles in the sea, between 20 and 200 meters from the coast, and that this reason, they could not migrate to the mainland (8 km) or vice versa." It makes sense, but he also listed other sharks as well as jaguars as "natural enemies of adult crocodiles". It is also possible that Medem just referring to other formidable predators capable of dealing with an adult C. acutes. I think great white shark are more than capable to take both juniviles and adult C. acutus swimming in sea, given the small size of this Crocodylus species in coastal habitats as well as the lack of reasons for migration for the largest dominant crocs. But this is just an anecdote from the locals, described with a small amount of detail... Look how much attention is paid to this anecdotal account in shark-crocs discussions, e.g. in the paper by James Nifong. Not sure what your first point is. Medem is quite clear that GWS is the predominant shark that was the enemy of adult American crocs and that the inhabitants of Fuerte Island observed GWS regularly prey on them, including the specific account of the apparent shark predation on the 2.3 meter croc. In fact the predations were frequent enough that the natives believed it contributed to the change in crocs migration patterns. That the jaguar and other sharks may also fight and/or prey with the crocs doesn't diminish the fact that GWS apparently regularly preyed upon this species. As to your second point, first I don't have any reason to doubt the testimony of the native inhabitants. They lived there and saw these interactions constantly, year after year, decade after decade. If anything their accounts should be given greater weight. As to the claim that American crocs are smaller in coastal habitats, it should be noted that most American crocs live in coastal habitats. I've seen no evidence that American crocs in Columbia or Fuerte Island are smaller than average, but if you have some citation to that effect, please provide it. |
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Post by Ceratodromeus on Mar 5, 2020 11:03:59 GMT 5
Apparently, it was somewhat common in the 50's. I've heard GWS are relatively rare there now, probably for a variety of environmental and natural factors. So I doubt it's common now. Haven't GWS been somewhat on the increase worldwide? It may become common again I'd doubt it was super common in the first place. |
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Post by Ceratodromeus on Mar 5, 2020 11:14:10 GMT 5
It makes sense, but he also listed other sharks as well as jaguars as "natural enemies of adult crocodiles". It is also possible that Medem just referring to other formidable predators capable of dealing with an adult C. acutes. I think great white shark are more than capable to take both juniviles and adult C. acutus swimming in sea, given the small size of this Crocodylus species in coastal habitats as well as the lack of reasons for migration for the largest dominant crocs. But this is just an anecdote from the locals, described with a small amount of detail... Look how much attention is paid to this anecdotal account in shark-crocs discussions, e.g. in the paper by James Nifong. As to your second point, first I don't have any reason to doubt the testimony of the native inhabitants. They lived there and saw these interactions constantly, year after year, decade after decade. If anything their accounts should be given greater weight. As to the claim that American crocs are smaller in coastal habitats, it should be noted that most American crocs live in coastal habitats. I've seen no evidence that American crocs in Columbia or Fuerte Island are smaller than average, but if you have some citation to that effect, please provide it. I believe he is referring to Platt et al(2009) {1}, in which the biggest animal found out of 92 animals classified as adults was 3.2m. Whether this is an isolated case in the species i do not know, but it is the one that comes to mind. The paper mentions the cause of smaller body size might be a result of overhunting. {1}www.salamandra-journal.com/index.php/home/contents/2011-vol-47/257-platt-s-g-t-r-rainwater-j-b-thorbjarnarson-d-martin/fileI also don't believe most American crocodiles live in coastal habitats, they are fairly widespread throughout a lot of the northern portion of South America's rivers swamps and lakes. Fairly pliable like most crocodiles and exceptionally more well spread than i think most realize. |
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Post by Bujang Senang on Mar 5, 2020 15:26:48 GMT 5
It makes sense, but he also listed other sharks as well as jaguars as "natural enemies of adult crocodiles". It is also possible that Medem just referring to other formidable predators capable of dealing with an adult C. acutes. I think great white shark are more than capable to take both juniviles and adult C. acutus swimming in sea, given the small size of this Crocodylus species in coastal habitats as well as the lack of reasons for migration for the largest dominant crocs. But this is just an anecdote from the locals, described with a small amount of detail... Look how much attention is paid to this anecdotal account in shark-crocs discussions, e.g. in the paper by James Nifong. Not sure what your first point is. Medem is quite clear that GWS is the predominant shark that was the enemy of adult American crocs and that the inhabitants of Fuerte Island observed GWS regularly prey on them, including the specific account of the apparent shark predation on the 2.3 meter croc. In fact the predations were frequent enough that the natives believed it contributed to the change in crocs migration patterns. That the jaguar and other sharks may also fight and/or prey with the crocs doesn't diminish the fact that GWS apparently regularly preyed upon this species. As to your second point, first I don't have any reason to doubt the testimony of the native inhabitants. They lived there and saw these interactions constantly, year after year, decade after decade. If anything their accounts should be given greater weight. As to the claim that American crocs are smaller in coastal habitats, it should be noted that most American crocs live in coastal habitats. I've seen no evidence that American crocs in Columbia or Fuerte Island are smaller than average, but if you have some citation to that effect, please provide it. My first point is that Medem mentioned other sharks and jaguars as enemies of adult crocodiles, despite the fact that he did not mentioned any predation/fight accounts other than attacks on Fuerte island. Then, return to my previous post: Medem could just list formidable predators that can take on adult American crocodiles, not necessary predators that are known to kill adult crocodiles. And the great white shark, as the largest macropredatory shark species, may just be the most dangerous adversary among all sharks... I really do not like such debates around very poor data on how to interpret them. We will never know what actually happened in the waters of Fuerte island many decades ago, because Medem did not leave any additional data. But the original quote in the paper just does not say that great white sharks attacked adult American crocodiles near Fuerte island and especially that sharks successfully killed them. P.S. about finding a dead 2.3 meter female crocodile, it is not even said that the wound looked like a shark bite. What do you think that it was the apparent shark attack? P.P.S. ok, in another part of the paper Medem mentions the same crocodile as "killed by sharks". It is not surprising that the great white sharks were able to mortally injure a 2.43 meter crocodile, even if it was not scavenged or just killed by another croc.
As for the second point, locals often give erroneous or inaccurate data. You probably know observation of the "megalania" killing a great white shark in Australia? Even if my interpretation is correct, and the "megalania" turned out to be a saltwater crocodile, the original data given by locals is still inaccurate. Point that the great white shark was responsible for decapitating the 3.5-meter Nile crocodile in South Africa was also thought by locals, and they even talked about some “teeth marks” on the croc's head. But after examination by rangers, it was shown that the crocodile definitely was poached (you will not say that the shark cut off the croc's tongue, right?). You must also remember "the 14-foot tiger shark killed by a saltwater crocodile" photographed & reported by some tourist, which is almost certainly a smaller bull or sand tiger shark. Which is quite funny, but sailors from the Seychelles interpreted rumble of thunder in the sea storm as noise from fights between crocodiles and sharks. We don’t even know what the locals said about great white shark attacks on American crocs in this case. It could be anything from real observations of shark attacks on crocodiles, to observations of crocodiles fighting each other or very indirect observations of sharks interacting crocs... Finally, I do not mean that alternative interpretations are probably true or that this account should be denied, because there is nothing improbable in that adult or even big juveniles of great white sharks, as well as large bull sharks (which could easily be confused with great whites), can take American crocodiles of unknown size, age and body condition, in this case including even healthy adults (see below for size of Fuerte crocs). My point is that such interpretations of this account as this data from Nifong (2017) are just ridiculous and should be ignored:
Now, regarding the size of American crocodiles. As far as I know, all reports of very large C. acutus come from large continental river systems. In the case of Crocodylus species there is a clear tendency: the larger sympatric prey, the larger crocodiles. C. acutus is a more fish-eater than most other large Crocodylus species, but still quite macropredatory and capable to take large prey. So, I do not think that C. acutus is an exception from this rule, and in any case population of large C. acutus needs at least rich fish sources for subsistence. There are no ways for the permanent existence of large crocodiles on the small islands, as well as there are no reasons for the migration of large adult American crocodiles to Fuerte, because this island was not described as a nesting place for sea turtles or something like that (but such islands is great places for young Individuals that was displaced out rich river systems by larger ones). Ceratodromeus already mentioned the paper that I would now refer to, and American crocodiles in Florida are also not very big. It is unlikely that crocodiles from a small island will not follow the same tendency to be smaller than crocs from large continental river systems. Medem reported that a 2.44 meter long female American crocodile from Fuerte was accepted by the locals as very large individual:  From Google translate: |
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Post by elosha11 on Oct 21, 2020 17:50:51 GMT 5
Lemon shark bites alligator
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Post by Ceratodromeus on Nov 27, 2020 1:13:42 GMT 5
Brief interaction between a sizeable saltwater crocodile and a smaller bull shark
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Post by Supercommunist on Dec 17, 2020 0:38:25 GMT 5
Edit just realized I posted this in the wrong thead lol.
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Post by elosha11 on Jan 17, 2021 8:04:33 GMT 5
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Post by Ceratodromeus on Jan 20, 2021 8:59:23 GMT 5
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Post by Ceratodromeus on Jan 28, 2021 2:57:47 GMT 5
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Post by Ceratodromeus on Jan 29, 2021 5:07:15 GMT 5
Significance of stingrays(Chondrichthyes: Myliobatiformes) as prey of crocodilians (Reptilia: Crocodylia) in non-marine environments"Stingrays (Myliobatiformes) co-occur with many crocodilians (alligators, caimans and crocodiles) in non-marine environments of tropical and subtropical regions. However, predation by crocodilians on stingrays is rare. Here, we report two predation attempts (one unsuccessful, one unknown) on Potamotrygon motoro, by a southern spectacled caiman, Caiman yacare, in Iberá Lake, Argentina. Based on these and other observations, we discuss the hypothesis that crocodilian predation is more common on sharks and shark-like batoids than on depressed
batoids, due to the fusiform body shape of the former two and the flattened shape of the latter. Within the literature, all recorded predation events on sharks were successful; one out of two observed predation attempts on shark-like batoids resulted in consumption. No successful predation attempts on depressed batoids were recorded,
although only one outcome was known out of the seven events observed. The prey/predator size ratio of one of our observed events (0.263) was similar to both the mean of all predatory events (0.312±0.060) and only successful ones (0.298±0.104), indicating that size was less important than prey shape in determining the outcome of the interaction. We reviewed the scientific literature on diet of South American crocodilians to quantify the prevalence of stingrays as prey. No stingray remains were found in any of the 7 species studied, based on 1339 samples. The low success rate of crocodilians preying on depressed batoids, the lack of stingray remains in diet studies of South American crocodilians, and the lack of rake-like marks consistent with caiman bites on living Neotropical freshwater stingrays indicate that predation by crocodilians on stingrays is very low. This should be taken as a working hypothesis in future assessments of predation on obligate freshwater elasmobranchs." www.pfeil-verlag.de/wp-content/uploads/2020/08/IEF_30_2_06_LU.pdfEmphasis mine.
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Post by Ceratodromeus on Jan 29, 2021 5:22:13 GMT 5
Probably one of my favorite videos of an American crocodile, eating a stingray in the surf off of Belize.
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Post by elosha11 on Jun 18, 2021 23:28:03 GMT 5
Interesting footage of what looks to be a bull shark interacting with a similar sized, subadult saltwater crocodile. I don't know if I would go so far as to say that shark was chasing or stalking the crocodile in any predatory manner, but it does seem to be a bit more aggressive and territorial in the interaction.
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