Dry environment tarantula species fasting patterns

[k2power]

I have often wondered if others have noticed as have I, that it seems that mainly the xeric scrub or desert dwelling tarantulas from the Americas are the main ones that go on prolonged fasts in captivity. I am thinking of mainly the Grammastolas, Brachypelmas, and Aphonopelmas. I know they are better adapted to undergo fasting but it often seems that they willingly do it while other tarantulas from moister environments don't do this as often or for as long. Does anyone notice that African or Australian species from deserts also willingly fast? Are there cues that initiate or break this pattern. I have seen 180 degree feeding pattern changes in an A. hentzi and B. smithi while others of the same species in the same room continue to feed regularly. Is it most common in adults. I don't see it in juveniles. Love to hear of others experiences and what species are most prone to fasting. Are there members of these genera that no one ever encounters fasting?

 

[Tarac]

Interesting question. It does hold true in my collection. Brachy's and Euathlus will sometimes fast for me, especially Brachy's. I don't even blink when they refuse. But if one of my Pokies refuses food and isn't due for a molt I do start to worry a little. I don't think any of my non-xeric species has gone through a significant fast. It sounds reasonable- slower metabolism, impressive longevity, etc. Just conjecture of course but definitely an interesting observation.

What initiates a fast? When I over feed to get rid of those last few feeders in the bin

 

[k2power]

I have only one Euathlus and it has never fasted on me. I am really curious what causes the fasts, especially with a former great eater. I have a B. smithi that was a fantastic eater and over the last year or more has really slowed down and is getting quite the small abdomen. and it is a confirmed female from a molt, so a maturing male is ruled out.

I also wonder if t is typically species that experience more temperate seasonal weather. I don't know if the "orange legged Brachys" have much of a winter though. I would expect the Chilean species do and certainly the native NA species do.

 

[Formerphobe]

Do we even know if these species deliberately 'fast' in the wild? Or, if they do so in captivity because of the overabundance of food offered?

 

[k2power]

I don't have an answer for that but would assume yes. I do know that temperate burrowing species will often seal their burrow openings with silk during the cooler season (A. chalcodes in a friends front yard in Mesa AZ) and it is removed when the weather warms. So that may last a few months I anticipate.

 

[Formerphobe]

I've not had opportunity to observe many in their natural environments. I have a mixture of CBB and WC Aphonopelma, Brachypelma and Grammostola species in my care, and across the board, their burrowing habits seem specific to reason and/or season. Most have created or have embellished 'pre-fab' burrows. Webbing over the entrance seems to be more of a 'doorbell', and I can usually see little spider feets behind the web door. If a prey item is introduced, most will go through the webbing to take the prey, then rebuild it when they're finished eating. If actively 'on the hunt' they will sit at or outside of burrow entrance with no webbing. If burrowed for their 'off' season or a molt, they create a more solid door of webbing and substrate. (I've also observed all of the above in my NW 'swampers' and many OW species.)

i.e. - I have three CBB Aphonopelma burica acquired a little over a year ago at 0.25 inch DLS. All had little shallow burrows in their 'infant vials'. In January, when they were each just shy of 1.0 inch DLS, I rehoused them into containers with a few inches of substrate. They all promptly burrowed as deep as they could go and completely sealed off burrow entrances. All three opened entrances and took prey items in early March, then resealed their entrances with web and substrate. All three opened entrances and took prey items in early June, appearing appreciably larger, and again resealed their burrows. All three reappeared almost exactly one month later in early July, obviously freshly molted (now 2+ inches with obvious blue fronts), opened up their burrows and started sitting out in the open, regularly taking prey.

On general Costa Rican climate:

The nation's climate is classically divided into two major seasons: rainy and dry. The dry season runs from January through May and the rainy season from May to November and December. Locally, the seasons were named by the early Spanish colonizers, who compared them to their own Mediterranean climate, calling the dry months "verano" or summer, and the rainy, grey and gloomy months "invierno" or winter. It is interesting to note that some of the coldest temperatures are registered during the early dry season or "summer".

http://www.worldheadquarters.com/cr/climate/

So, even though CBB, my guys/gals were burrowed through their native dry 'summer', during which are some of the coldest temps, only poking their noses out once in mid season for a meal. Then they came all the way out when the 'winter' rainy season was well under way.

I rehoused them again last week into bigger, better digs. They are all currently customizing their 'pre-fab' burrows, but are almost always seen sitting outside the burrows proper. They've each taken one prey item per week since their re-emergence in early July. I practice a 'If I don't see them, then I don't feed them' protocol.

I would add that all of my tarantulas live in my bedroom and I don't go to any great pains to adjust temperature for them. House temps range between 68 - 78 F through the year.

I think applying the human perception of 'fasting' to tarantulas is, well, anthropomorphic. In the wild they eat according to availability which corresponds with season. In a captive setting, many will continue that cycle. In captivity some opportunistic individuals, or species may eat to the point of gluttony resulting in their own demise. Or, to a point where they 'say', "OMG! I'm so full I absolutely can't eat another bite for at least 6 months..."

 

[k2power]

Fasting is just a description that explains what is happening. And yes we aren't sure what is going on to cause it. It is definitely individual to particular spiders when others of the same species or genus in the same room feed regularly. I currently have a WC A. hentzi I found in MO and a Craigslist acquired B. smithi that are fasting. The hentzi has only eaten a half dozen times since I caught it in July 2011 but seems of good weight. The B. smithi has been in my possession 2 years and ate great the first year and abruptly stopped feeding regularly. It still eats the equivalent of 1 or 2 insects (crickets or superworms) every 2 months but shows signs of getting skinny. October seems to be its molting period so hopefully it will molt soon and snap out of its fast. The reduction in abdomen size is noticeable and has me concerned to say the least. The other 28 or so spiders I have are a mixture of NA, SA, African, and Asian species from all kinds of environments and all eat regularly. There is something to these few genera it seems that is not commonly found in other genera.

Does anyone have tarantulas from xeric environments in Africa, Australia or Asia that fast like the American species often do?