Fall bat events (updated year of the bat listing)

Below is an updated listing for October of events from around the world that relate to bats some in celebration of the Year of the Bat (2011)).
(In-progress, expect updates)

Australia, New Zealand, New Guinea, South Pacific Islands
31 October Australasian Bat night

Europe
France
26, 29 Oct. Bourges Chauve-souris expo at the Natural History Museum in Bourges.

Germany
3 Oct. Fledermaus Kreativ Wettbewerb (bat creativity contest to come up with art for the bat museum or Internet site.)

Sweden
23 Oct. Opening of Sweden's bat museum!

Switzerland
1 Oct. (Zurich) Long Sat. bat exhibit.

United Kingdom
21 Oct. Bats for building workers (workshop) Jersey Bat Group.

North America
Canada
26-29 Oct. North American Symposium on Bat Research (NASBR). Toronto, Canada. Chiropterologists will be meeting to discuss their research!

United States
Austin, Texas.
Anytime. Who knew? You can take river cruises to see the famous Congress Avenue Bridge bat colony emerge! So the next time you are in Austin check it out.

Bat souffle anyone? Milk assays in-progress

It has been some time (and then some) since I have posted anything but I figured a quick update about my current endeavours: bat milk analysis would get me back to posting more regularly. Besides classes start up tomorrow so I am back to my regular schedule and so too blogging.

Because I am interested in the costs of reproduction in bats I am also very interested in the quality of the milk bats produce. This is in part because lactation is arguably the most expensive task that mammals do! Females will deplete their fat stores and even start to break down their own skeletons to make milk for their young.

But here is the issue. Bats are MUCH smaller than cows.

So say I want to know the percentages of fat, sugar and protein or total calories in bat milk... I will need a LOT of milk or very specialized techniques to evaluate these components. This is where an amazing group of people come in one of which is Dr. Wendy Hood at Auburn who has developed methods to analyze very tiny volumes of milk!

Thank you Dr. Hood! So since last September I have worked off and on to develop my own versions of these tests using the methods and protocols of Dr. Hood.

My standard for all my tests (to be sure they are working) happens to be regular 'ol cow's milk. Luckily the values for all the parts of cow milk are all well known (thank you now to the USDA!) * see label above for an example.

The idea (one that takes more work than it sounds) is to get the same numbers for your cow milk as the contain of milk suggests... if you can do that your assays are working!

The parts I analyze are:

• dry mass (how much water is in the milk)


• fat


• carbohydrates (sugars like lactose) and


• protein

If you know these components you can calculate the amount of energy in your milk!

I will explain each of these in part but the bat souffle will be first so... keep posted!

Pitcher perfect- a strange mutualism

Carnivorous plants like the Venus flytrap capture insects and digest them to obtain protein (which is made up of Nitrogen). What could a bat and a carnivorous plant have in common? Recently, a group of German researchers demonstrated that these two organisms can develop a mutualistic association. (Mutualisms develop when both partners of a relationship gain something through their association with the other individual, many examples of which occur nature).

This fascinating study conducted in Brunei demonstrated that bats use pitcher plants as roosting sites and in turn the nitrogen rich feces (guano) from the bats fall into the pitcher of the plant where it like the insects the plant usually digests is incorporated into the plant's tissue.

The bat (woolly bats (Kerivoula hardwickii)) is provided with a place to live while the plant (areal pitcher plant (Nepenthes rafflesiana) gets its highly sought after nitrogen!

The precarious roosting location for the bats aside this fascinating study that uses both radio telemetry and stable isotope ecological methods reveals an unlikely relationship between carnivorous plants and bats.

The article:
Grafe, T. U., C.R. Schoener, G. Kerth, A. Junaidi, and M.G. Schoener. (2011). A novel resource-service mutalism between bats and pitcher plants. Biology Letters

Updated bat activies for May 2011 (year of the bat!)

An updated list of bat related activities around the world in May to celebrate the 'Year of the Bat'!



Unfortunately activities seem restricted to Europe for the time being...



EUROPE

Germany (Frankfurt)



11 May Nachtscwaermer-guided tour (Frakfurt Zoo)



18 May- Nachtscwaermer- guided tour (Frankfurt Zoo)



21 & 22 May- Experiencing bats (Frankfurt Zoo)



25 May- Lecture "night Flight- Fascinating bats" (Frankfurt Zoo)



UK

17 May Bat walk, Bryngarw County Park, Bridgend, South Wales



20May- 16 September Cambridge, 'Bat Safari' river tours

Back to field planing! (and milking bats)

Ah it is 'that time' again the birds are singing, the bees are buzzing and the bats are lactating! Yes, considering that the Artibeus were all pregnant (late-stage) during my mid-march visit if I plan on collecting milk it is time once again to schedule a trip to the field for the 'last' milk collection of my dissertation (assuming all going according to plan). This next trip my lab mate will accompany me which will be an added bonus. Now all that said I imagine one question came to mind rather quickly 'wait... milk bats?' Yes... this is actually not as difficult as it sounds. Basically the mother and pup are captured, kept away from each other for a short while (~1 hour) so she accumulates milk which is natural if the mother is away from her baby. (Also the mother and pup are accustomed to being separated from each other for longer periods of time because the baby that cannot fly must stay behind while its mother is out for several hours every night searching for food.) After about an hour, I inject the mother with a small amount of a hormone called oxytocin. Oxytocin increases milk let down (i.e. lactation) so this combined with what is essentially a miniature version of milking a cow allows me to collect milk from the female before letting her and her baby return to their roost. I then upon returning analyze many nutritional components in the milk (dry mass, protein, fat, and carbohydrate (sugar) content).

Flight (Part 2)

Continuing on the topic of flight... The physics of flight include 4 forces. 2 of these (in bold) are generated by the flying animal (in this case a bat) and 2 of them (drag and gravity) are natural properties that the animal must negotiate (fight) in order to fly. 1. Lift (i.e. upward force) 2. Thrust (i.e. forward force) 3. Drag (backward force (resistance)) 4. Gravity (i.e. downward force)

LIFT

The shape of wings causes air to move over the wing-surface in a unique way. Specifically, air flows faster over the upper curved surface of the wing and slower over the cupped (concave) surface. This causes negative pressure on the upper side of the wing and thus the wing begins to rise. In principle this is what happens when as a child you cupped your hand and played with the wind outside the open car window. Remember how the air would suddenly PUSH your hand upward? That is 'lift'! Additionally that is about the time you were reminded to not put your arms out the window.

Take home: the shape of wings (think of a bird or bat wing) is what causes air to move in a way that LIFTS the wing upward. The opposing force is gravity... without lift (like you or I flapping our arms, sorry to say but we are not going to generate sufficient lift) gravity 'wins' and we stay stuck to the ground. Gravity is complex for despite the fact that physicists can tell us its value (9.81 m/s2) how it 'works' and why it exerts force on objects was perplexing even to Einstein who wrote extensively on the topic. Incidentally, Einstein apparently also noted "Gravity cannot be held responsible for people falling in love." ______________ (I will insert an awkward pause here as you ponder that and why he might have felt it necessary to declare such a fact, if he made this statement in English or German and if it would have been funny regardless). Back to flight: The wings of bats are more flexible than birds because the wing itself is formed by a thin layer of skin rather than stiff feathers. However, birds are able to more easily change their wing area by moving their wings closer to their bodies because bats require the full extension of their 'fingers' i.e. the wing to have it function because of its thin nature. In searching for an analogy the best I have for you follows. This is similar in a way to how airplanes have rigid wings (like bird wings) while a para glider that uses a flexible surface (like a bats wings) is less able to change the shape of the 'wings' or they will loose lift.

THRUST

Basically thrust is the power from a wing-stroke that pushes back against air and results in a force propelling the animal FORWARD. Indeed to understand this idea you must remember that air is made up of molecules and is in actuality a fluid (like water). Thus there is indeed something to 'push upon'.

I will conclude for now and leave you with another Einstein quote as a 'token' physicist

"Science i nothing more than a refinement of everyday thinking".

I refer you to this much more comprehensive explanation of flight (here) and hope you find this topic interesting.

The evolution of flight (Part 1)

Many animals are able to fly and most of these are insects. However, when one stops to consider which vertebrates fly (vertebrates are animals with an internal skeleton including a spine and something resembling a spinal chord) only 3 main groups are able to fly.

These are: birds, Pterosaurs and bats.

The wing surface formed in 3 different ways one for each of these groups (see above).

Both bats and Pterosaurs used a wing-surface created by finger elongation (the 'pinkie' in Pterosaurs and all fingers elongated except the 'thumb' in bats).

Meanwhile, birds fly using a surface created by modified scales (feathers) and a strong series of arm and finger bones that are the result numerous bones fusing. Additional details are left out for brevity but are extremely interesting such as skeletal lightening in birds.

Pterosaurs are extinct and so only two extant flying vertebrate groups (extant = animals that are still alive today) are bats and birds. (What is a Pterosaur? Click here!)

Why did flight evolve?

There are two main thoughts about this. Basically either animals were able to flap and lift UP to escape predators etc. OR they were living in trees and started to glide from tree to tree (like 'flying' squirrels) also to catch food (insects) or avoid predators.

Regardless, the sky is (and was) full of potential food and once they were able to fly bats quickly filled a new niche (a niche is the ecological role of an animal generally relating to the food it eats). Both bats and birds were able to eat flying insects but bats as nocturnal animals compete with a fewer set of birds. Indeed this successful niche 'nocturnal insectivore' has since been radically expanded to include other more unusual food-types such as frogs or fish!

You can read more about the evolution of flight here.

Click here for cool videos of bats flying in slow motion.

For my next I will try to summarize the physics required for flight.