Small Mammals - Science topic

When food energy is moved from farmers to herbivores to carnivores, only 10 percentages of the energy is transferred from one trophic stage to another trophic level. The right answer, therefore, is 'Herbivores have higher energy transfer performance than carnivores. The average efficiency of energy transfer from herbivores to carnivores is 10%. Carnivores have higher consumption efficiency than herbivores, since more of their food source is consumed than enters into the detrital food chain. Assimilation efficiency varies with prey type, with AE for herbivorous species generally ranging from 60 to 95%, and carnivorous species higher, at more than 90%. We compare digestive physiology of mammal herbivores and carnivores. Carnivores have lower intake, higher digestibility, shorter digesta retention. The scaling of these measures with body mass is nevertheless similar between the groups. As a consequence, carnivores have less gut fill than herbivores. The total bioavailability of plants vastly exceeds that of animals, so an average ecosystem can support many more herbivores than it can carnivores. This means, by random chance alone, it is more likely for the strongest species or individual to be an herbivore. The small intestine is longer in herbivores than in carnivores because herbivores consume plant and grass-based food which is high in cellulose and the digestion of cellulose takes a long time. The length of the small intestine differs in various animals depending on the food that they eat. Higher reproduction and longevity was apparent in omnivores compared to herbivores. However, there was no significant difference in reproduction or longevity between herbivores and carnivores. Birds and small mammals have low net production efficiency because of their high metabolic rates, which consume a substantial portion of the energy they acquire from their diets. Endotherms like birds and mammals typically have low production efficiencies due to the larger quantities of energy spent maintaining constant high body temperatures, and high metabolic rates. The production efficiency of herbivores tends to be higher than that of carnivores. Generally, an individual's production efficiency will decline as the C: N ratio of its food increases All else being equal, small animals have lower production efficiencies than large ones.

Larger mammals also have less body surface area for a unit of body mass, and therefore have slower heat loss per kilogram of body mass, in cool environments, than do smaller mammals. Body size is a factor because the greater the surface area of the body relative to its mass, the more rapid will be its cooling. Since animals exchange heat with their environment across their body surfaces, small animals will tend to lose heat to a cooler environment faster than large animals. Structural mass involves maintenance costs, reserve mass does not. Hence, small adults of one species respire more per unit of weight than large adults of another species because a larger fraction of their body mass consists of structure rather than reserve. The good news is we already have a pretty good idea why large animals often live longer than small ones. It has to do with the fact that tiny animals are more likely to be gobbled up by predators. These animals tend to have babies early and age quickly. Generally, the smaller the animal, the faster its heart beats. Several studies of human populations around the world indicate that there is a relationship between low birth weight and high blood pressure in adult life. Giraffes' blood pressure is about twice as high as most other animals. The reason small animals often have higher metabolic rates than larger animals are that smaller animals have a higher ratio of surface area to volume. This means that small animals lose body heat faster than larger animals. A small body has a relatively large surface area compared to its overall size. Because heat is lost from the surface of the body, small mammals lose a greater proportion of their body heat than large mammals. Energy is lost with each trophic level, so it takes more of the sun's energy to ultimately produce a pound of meat to feed a carnivore than it does to produce a pound of plants to feed an herbivore. 10% of energy is passed from one trophic level to the next. The next consumer on the food chain that eats the herbivore will only store about 10% of the total energy from the herbivore in its own body. This means the carnivore will store only about 1% of the total energy that was originally in the plant. The reason for this is that only around 10 per cent of the energy is passed on to the next trophic level. The rest of the energy passes out of the food chain in a number of ways: it is released as heat energy during respiration. The average efficiency of energy transfer from herbivores to carnivores is 10%. The initial energy source is found in the plant. The plant uses initial energy from the sun to convert into chemical energy via photosynthesis. The herbivores eat the plants, ingesting some of the energy from the plant of the energy. The herbivore then becomes prey their energy is transferred to the predator.Therefore, when the herbivore is eaten by a carnivore, it passes only a small amount of total energy to the carnivore. Of the energy transferred from the herbivore to the carnivore, some energy will be “wasted” or “used up” by the carnivore.

Hello all; Science Magazine (28 Apr 2023) contains a series of papers that directly address this topic. Ruben's comment is specifically relevant. Best regards, Jim Des Lauriers

There are classic sources that should help direct you in your quest for a unitary colonization model. Clearly, colonization cannot occur without survival (and I would say the Allee Effect is more a model of population decline and extirpation/extinction than of population colonization).

The environmental context in which a given possible colonization event is occurring is key. Island Biogeographic Theory would be informative here -- see: MacArthur & Wilson (1967) - The Theory of Island Biogeography; MacArthur (1972) - Geographical Ecology; Brown (1995) - Macroecology. Lots of graphical figures in these sources that model possible survival trajectories and outcomes of population colonizations. But, the context of any given population colonization event/process is pivotal -- this is likely a key reason you are finding it difficult to conceptualize a unitary model for population colonizations. The classic MacArthur & Wilson colonization scenario where a founding population reaches an off-shore island is just one conceptualization (e.g., there would also be need to consider whether the island was located on a continental shelf adjacent to the mainland source region for a colonizing population, or whether it was an oceanic island). Of course, the "island" conceptualization also applies to habitat blocks (e.g., protected areas) in continental regions. The taxon/taxa involved in the colonization(s) you are looking to model would be another significant variable to consider... you mention a small mammal community -- how many mammalian orders are represented? What is the body size range? Such model parameters would undoubtedly be different for mammalian taxa (as opposed to amphibian, reptile, avian, or other taxonomic groups), and could also vary considerably across different mammalian taxa (with body size being a prime limiting factor in colonization events and outcomes).

Great question. I have gone through the same issue while laying baited pitfall traps and have sadly captured reptiles in the trap, along with my study group of beetles. Please do checkout the discussion thread here for some ideas : https://www.researchgate.net/post/How-to-prevent-that-small-vertebrata-get-caught-in-regular-soil-pitfall-traps

I would also recommend you to go through the methodology followed by where their intent was to capture small vertebrates but exclude larger predators like mammals? Might be useful.

Hello Kyle , you can only estimate a linear regression between body mass and reproductive class, if the reproductive class is a continuous variable, otherwise you cannot use it. As for the test of difference in body mass during the season, it is interesting. But I advise you to do the test comparing male and female in each season (t-test), it would be more interesting. Hope this helps

Hi!

The following paper might be a good starting point to find more identification guides.

"Identification of Shrews and Rodents from Skull Remains according to the Length of a Tooth Row" (Balčiauskienė et al. 2002)

doi: 10.1080/13921657.2002.10512524

Search :

Crouched Locomotion in Small Mammals: The Effects of Habitat and Aging

by Angela M Horner (2010)

Dear Jan Gojznikar

These links might be helpful, have a look:

1. https://atstrack.com/animal-class/mammals.aspx

2. https://celltracktech.com/products/cellular-gsm/es400-gsm-gps-tracker/

3. https://www.telemetrysolutions.com/wildlife-tracking-devices/

4. https://wildlifeact.com/blog/gps-and-vhf-tracking-collars-used-for-wildlife-monitoring/

Kind Regards

Thank you for your answers! J. C. Tarafdar Andrew Paul McKenzie Pegman

I would check other values like head-body length to see if there is intrapopulational variation. If the discrepancy is really due to intraspecific variation you would expect linear dimensions to show a similar pattern to body mass, since you would be measuring bigger dimensions on bigger animals.

However, it's also possible that the reported body masses are just plain discrepancies. I've noticed a lot of second-hand databases like PanTheria can be extremely inaccurate when it comes to reporting body mass values because they often just collate them from the previously published literature. A lot of times studies will use ballpark values or the midpoint of guestimated ranges from sources like Walker's Mammals of the World, which aren't very accurate or precise. A good example of this is the South American rodent Dinomys branickii. Most studies using body mass for Dinomys will report a value of 10-15 kg or 13-14 kg, which seems to be drawn from a ballpark range of 10-15 kg mentioned in a paper from the early 20th century (maybe Allen 1942). This doesn't appear to be based on any measured specimens, and no studies list specimens from where these data were collected. However, actual weights of Dinomys based on first-hand measurements of collected wild individuals (e.g., Osbahr et al. 2009, Gottdenker et al. 2001) finds that the body mass of Dinomys is actually only about 9.5 +/- 1.1 kg, a much lower estimate. Larger individuals are known but are highly gravid, captive ones. Nevertheless, people have been reporting a 13-15 kg body mass for Dinomys as if it were gospel.

Hello Russell: Tungsten carbide is used as an abrasive. It comes in grit sizes that vary from extremely fine powder to pretty coarse grit. If you can get permission from collection managers, a heat sterilized jar of the grit of whatever sizes you determine to be appropriate, non-toxic and pest-free. A graduated cylinder provides the volume directly. Were I a collections manager, I can't imagine what the problem would be.

Apparently specimen loans are out of the question. Hmmm.

Best regards, Jim Des Lauriers.

Dear patrick .

please see attach paper

Best Regard

I don't know if i understand right, but if I did, I think that you need to build an experimental area where you will have both situations, fenced and non fenced large areas, which you'll monitorate to observe the major differences between then in respect to the behavior of the native species. In this case, since you're trying to understand the effect of the fence in the native species, non fenced areas would be control areas and fenced areas would be the ones that you would add treatments that emcompass the main questions you want to elucidate. A list of the species that naturally occur in the area can guide you in respect of how the fenced areas + treatments are affect the transit of them in comparison with the control area.

Hi James. Thank you for your input. I have tried twisting rabbit bones to access marrow and while I agree it is very effective, I am more interested in other methods of accessing marrow that may have been used in the past. It looks like no one has done this so I'm looking into conducting one. Thanks again.

Thanks! I will check it!

Nora Whittle

Many studies have linked this resistance predominantly on indirect association. but few new articles have described this on high use of antibiotics in humans without prescription, improper dosage and stopping the schedule before prescribed time.

We've had our fair share of images of birds (mostly owls) even small ones and monitor lizards (not ant other reptiles) in our camera traps as bycatch data. I hear Reconyx is good, we use Cuddeback which is also good. Depending on which species you focus, you may want to have specific cameras and field designs.

I do a lot of reviewing and I wish you well.

For my own papers I follow a simple rule: what? Why? How? What happened? So what? It's a circle.

I can't take credit for inventing the questions

All the factors already mentioned are likely to affect wild boar populations growth but as my colleague Oliver Keuling have explained the problem in North Africa at least in Algeria and I think in morroco and Tunisia also, is the fact that it does not exist a management plan for wild boar hunting. We hunt for leisure so we miss information that allows us to have an overview on population trends.

We can say that wild boar populations are increasing, decreasing or stable if we don't have an evaluation indicators Oliver Keuling .

Best

Fatima

See article: The Hunting Trends of Wild Boar (Sus scrofa) Hunters in Northeastern Algeria.

If the Kruskal-Wallis and/or the Anova tests are significant, run a Post Hoc test. These are sufficiently available in most statistical software packages.

It depends on how you want to roll this up. Presuming that you checked traps on multiple occasions through time, you could do an occupancy analysis at the scale of individual traps. However, depending on the movement ability of your small mammals relative to the distance between traps within a plot, it might make more sense to do an occupancy analysis at the scale of the plots. Here, the plot is occupied if one or more traps have a captured animal at a given time step. But now you have richer data than 0/1 because you could actually have anywhere between 0 and 40 "hits". There are extensions of the classic occupancy analysis that can accommodate this extra information that are called "multi-state occupancy models."

Since you have habitat data, you can either include that directly as a (continuous) covariate or you could use the land use categories as a discrete covariate.

Since you are asking what the number of occasions is, I suspect that you did not actually check your traps multiple times through time...

Different species but the Vincent Wildlife Trust did work on pine marten personality traits to inform which individuals might be best used in reintroduction projects. Contact information here:

Admir,

We used Moultrie M-880 with a photo burst of 3 pictures at a time for Allegheny Woodrat (Neotoma magister), and small carnivores (Long-tailed weasels) in mountainous areas of Virginia. These setting allowed us to capture quick moving animals (weasels), smaller rodents such as voles, Peromyscus sp, as well as larger Neotoma sp.

I also recommend you check out the publication " A novel method for camera‐trapping small mammals" by McCleery et al. (2014).

Cheers,

Jason

To measure oxidative stress in small mammals you can use CAT-catalase, SOD-superoxide dismutase and GST-gluthatione -S-transferase in blood and liver tissues.

Since the information you provide suggests that the invasive species is not a target of your project, then not releasing it back into the wild will not bias your results.  I am sure your project is guided by ethical rules (established by your host institution), but the Ethics Board may not have specified what must be done with bycatch or indeed injured target species.  It is in the best interests of the park for invasive species to be eradicated, but as individuals your group might have issues with euthanising animals on an ad-hoc basis.  My approach would be to discuss first with the park authorities - perhaps by highlighting this question, it will at least draw attention to the issue of invasive species in the park (and might even be adopted as a pilot eradication project) if these invasives do indeed have a serious negative impact on the native fauna/flora.

The Senckenberg institute in Germany has experience with the species you mention. 

Hi Seiji San,

I asked my colleague to give me a cup of feces of Schisto. I will send it to you soon.

Best regards

Amel

Hi Delson,

You probably have this already but just in case :)

Rodents of Sub-Saharan Africa: A biogeographic and taxonomic synthesis

By Ara Monadjem, Peter J. Taylor, Christiane Denys, Fenton P.D. Cotterill

Until the nine months of age the Epiphyseal Protrusion of the ulna is notorious in the lagomorphs ( In older specimens  disappears).

Crystalline lens weighing techniques are also used.

See: http://rcin.org.pl/Content/10127/BI002_2613_Cz-40-2_Acta-T17-nr7-75-86_o.pdf

Check also these two publications:

Best regards

In Hoffman's and Poorter's case, bias of variation in RGR over the time period was removed with natural logarithmic transformation. However, transformations can also introduce bias! So I think the answer is that you need to do your own experimental tests for each of those growth parameters. 

follow this link of manufacturer for the same columns as for Qiagen with lower price.

hoping will help you.

Francien:

This link and the references therein might be helpful:

Best

Syed

I also prefer Tomahawk traps.  Just make sure to check the ends of the wires - sometimes they can be pretty sharp, and can injure little paws as they try to dig around the trap.  A flat file can be used to take off the sharp edges.  Too large a trap can be a problem if the mesh size is big enough to get their nose through.

Gracias Alejandra!!!

Hi Niko,

If you're trying to compare the four land units then you will eventually need to contrast four values for each parameter. You also have 6 plots for each season so you have spatio-temporal data. Spatial: four plots/locations and temporal: 4 seasons.

You can start with exploratory data analyses for each plot then for four of them one season at a time. For the 6 quadrats (in each unit), you will need to investigate:

do they statistically significantly differ from each other (mean & variance tests)? If not then you can combine them into one variable. If they were different then you'll need to figure out if this is consistent for the four units.

Going back to your initial question of whether they correlate or not, you'll need to decide which variables to contrast against each other (pair-wise comparisons), which goes back to the spatio-temporal aspect of the many columns/variables you have.

Hope this helps.

Don't worry, the idea is the same. You just repeat values of variables as you need in your columns. It doesn't matter whether you have repeated measures on different units.

Cheers

Christian,

Thanks for the quick response. I am familiar with the Sarjeant & Langston monograph. The mustelid tracks they describe have much shorter digit lengths, and the digits terminate in curved claws. The  amphicyonid tracks (ichnogenus Axiciapes) have very short, broad digits.  Sarjeant, Reynolds, and Kissel Jones (2002) described a different amphycyonid Miocene track from California (ichnogenus Herpexipedes). Those tracks have elongate digits, but the size is much larger than the Washington tracks. Also, the interdigital angles are quite narrow, almost parallel. The Washington tracks have much broader interdigital angles.

Best wishes, George

Are you kidding me?

My latest paper fits seed dispersal distributions occurring over two weeks (or less) to Weibull curves: see DOI: 10.1111/ecog.02191 – it will be online in Ecography very soon. And available from me on this site soon.

Andrew :-)

Philander opossum is the scientific name. In México, we know that this marsupial have the commun name of "Tlacuache cuatro ojillos", due to upper white dots in its eyes. Is a female and she has a frontal bag where bring on its little babies. Thanks for sharing.

Dear Mehmet,

Thank you very much for your recommendation. I will take it into account.

All the best,

Jasmin

Hi, I think you can do discriminant analysis using three groups of spécimen, FULLY, NAKED and MEDIUM. 

you can see also the document of BERENGERE 2003.

I can help you in the analysis if you need.

Hi Haya,

after some googling there can be found at least:

Hi HB: 122 (115-130) mm, n = 7

T: 106 (80-120) mm, n = 7

HF: 31 (30-35) mm, n = 7

E: 11 (10-12) mm, n = 7

WT: n.d

GLS: 34.8 (33.0-37.0) mm, n = 7

GWS: 21.5 (19.6-23. 1) mm, n = 5

M1-M3: 5.7 (5.2-5.9) mm, n = 7

HB 131-150; T 88-117; HF 31-34; E 17;GLS 36—38

The two Acomys were harder to find. Maybe somebody has actual measurements to share.

Cheers,

-Kari

Dear all,

My Gauthier-lab at Laval University studies lemming populations in an Arctic island since ~15 years now. Lemmings are ~ 20-50g. They are using a trapping grid and live-trap with baits (piece of apple as bait and they put cotton wool for a cosier trap ^^). Here are 2 references (with pdf) of their published study. They marked lemming with PIT-tag and use readers for individual recognition.

You could try to contact Dominique Fauteaux (current PhD student on lemming - present in ResearchGate) for more details about the study design.

For what I've seen during fieldwork (I was working on goose but also help sometimes on lemming project), there were some death due to heart attack but none due to infection.

Cheers,

Guillaume

Related my field experience setting traps, the rodent communities in Southeast Asia are mainly dominated by big rodents (i.e.: genus Rattus, Bandicota), so probably bottles cannot act as trap for adult individuals.

I have not seen areas with discarded bottles, probably as they are collected to sell (glass and plastic), probably not happening this in the Northern hemisphere.

Probably this two factors can contribute in some way to this bias of information.

And L. Mike Conner comment can also be right.

Tanvir -

I am glad you found our paper interesting, but I have to add that these are relative densities, which is not the same as absolute densities let alone population size. Relative densities and absence-presence data are important, but in order to get the absolute population size you have to use other methods as indicated in the previous discussion.

Cheers, Andreas

best source in Germany:

Jenrich, J., P-W. Löhr & F. Müller (2010): Kleinsäuger, Körper- und Schädelmerkmale, Ökologie. Verein für Naturkunde in Osthessen e. V. Fulda. 340 pages. ISBN 978-3-86568-147-8

(with excellent graphs ans photos)

Having prepared the nasal cavities of mice, I can recommend the following:

1.  Perform perfusion-fixation on your animal if at all feasible.  Tissue should become stiff.

2. Decapitate, remove skin from the head and immerse the entire head in a 10x volume of fixative overnight.

3. Rinse out fix, and decalcify well using HCl- (faster) and/or EDTA-based (slower) solutions.  (We use Cal-Ex from Fisher, but you can make your own.)

4. When the decalcification endpoint is reached, trim area around the organ into a < 1 cm cube, dehydrate in graded ethanols and embed in parafffin.

5. Section and stain with your choice of protocol.

Some metals (lead if I remeber correctly) act as bone homeostasis interference... so, you have to digest bones to quantifiy the metals... I don't know if beetles break bones....

Blood can be more easy I thinl

I suppose you can use the mini GPS trackers used for birds. There are several company who made such units.

Hi John!

Unfortunately my photos of Pteropus rodricensis are really of poor quality (and I do not have any of the skull). I suggest to ctc 

Mauritian Wildlife Foundation

Grannum Road

Vacoas

Mauritius

Phone Number (230) 697-6097

Fax (230) 697-6512

Email executive@mauritian-wildlife.org

Website Address http://www.mauritian-wildlife.org

or

Mauritian Wildlife Foundation

Forestry Quarters

Solitude

Rodrigues

Phone Number (230) 831-4558

Fax (230) 831-4559

Email mwfrod@mauritian-wildlife.org

Website Address http://www.mauritian-wildlife.org

or

Mauritius Natural History Museum

under Mauritius Museums Council

All the best.

Marco

I used nail varnish to paint the toe nails of small mammals. I got the best results when using fast drying ones with glitter inside.

But if you want to recognise the animals after more than 3 days I would prefer fur clipping!

I have found similar performance across many different brands of cyanoacrylate-base glues.  One trick that often helps is the wet the hair of the small mammal in the area where the glue will be applied prior to glue application.  The main advantage of this may simply be that it gets hair out of the way so that the glue bonds to skin but it seems to help.

Try Mammalian Species. It's online.

I don't specifically know Lorna- I used to share on office with someone who had two captive bred males-they used to fight viciously on a regular basis so they are capable of aggressive behaviour and I believe infanticide was a regular occurrence in the captive breeding colony that used to be held here many years ago for behavioural studies.

Hi Steven, you could also try this company in the UK www.danfield.co.uk/, we used their bobbin spools for tracking movement patterns of frogs and snakes etc in Peru and at the time they said they could probably post to South America if we needed extras.

If an artificial nest box is an option, then this is relatively straight forward for indirect calorimetry. If using a pull mode configuration (i.e. measuring excurrent flow rate) the box does not even have to be perfectly sealed. If providing nesting material, make sure it is not rotting, a "compost heap" can have a quite high metabolic rate on its own. Especially, when comparing it to a hibernating animal.

You can calculate the EEG power as a parameter. The total power would be lowered  in rats dependent on the depth and duration of anesthesia. And the gravity frequcenty would be another parameter (be lowered too).

The correct binomen is Dromiciops gliroides, because Philippi described the same species in 1893 as Didelphys australis, a name preoccupied by Didelphys australis Goldfuss, 1809 (= “Pennants New Holland opossum, a phalangerid”, according to Hershkovitz, Ph. 1999. Dromiciops gliroides Thomas, 1894, last of the Microbiotheria [Marsupialia], with a review of the family Microbiotheriidae. Fieldiana [Zool.], N.S., No. 93, page 26; the identity of the latter species remains obscure, though).

It depends which immune response you want to measure and what kind of samples you have...

- for complement: Bacterial killing activity (plasma)

- inflammatory response: haptoglobin concentration

- for complement/ natural antibodies: Hemolysis Hemagglutionation assay

- for phagocytosis: Bacterial killing activity (whole blood) 

- for humoral acquired: IgG Levels (ELISA) 

- for cellular: blood smears / lymphocyte proliferation assay

Actually there is a very good paper concerning how to assess immune reponses: Demas et al. 2011 J Animal Ecol: Beyond phytohaemagglutinin: assessing vertebrate immune function across ecological contexts

I’m guessing these differ vastly from one weevil species to another. What follows is strictly for species with larvae developing inside fruit; those with larvae in the soil, leaf-rolling etc. are completely different matters. Oviposition sites are probably important in many weevil species, both common (those dependant of an abundant resource that may nevertheless fluctuate from year to year – may be your case) and rare (those where the plant may simply produce zero fruit in bad years). I would however not discard parasitoid wasps, especially in abundant weevils. I’d expect a fair bit of recent research, though old sources like Fabre may yet be a good place to start.

Hi, I suggest you should place your transects parallel to the edge you are interested on. So, you will have a similar trapping effect along each transect regarding distance from the border (the whole transect will be at the same distance from the border). Each transect could be placed at different distances from the border and then you will be able to evaluate the differences between different transects at different distances. Moreover, you also have to place several sets of transects in different sampling points. I mean you should not place several sets of transects in a same fragment, for example. Instead, it would be better to place one set of transects at different distances in several fragments, thus you can have (spatially) independent sampling points to analyse. Good luck!

Thanks for all your answers.

The rarefaction suggestion is a very good one. I'll try it. Thank you Lauri Kaila and Jose Luis Carballo.

Eric Marboutin, the bootstrap is also possible. Thank you.

Matt Nicholson and Sujan Henkanaththegedara, the problem with indices like number of caught per trap-nights is that not necessarily the relationship between the number of captured individuals and sampling effort is linear; probably is non-linear. Some papers already discussed it and discourage the use of it.

Fernando, we do mark and release the marsupials. We have 3 trapping grids with 25 trapping stations; in the beginning of the study, live traps were placed on the floor and canopy. After 2009, we added in all trapping stations one more trap in the understory.

About SECR, I already though about it, nonetheless I never really got in contact with it so I didn’t know that I could use it to correct the increase in the sampling effort. Do you think it is possible to determine the three elevations in the analysis?

Matt W Hayward, I agree with you about the use of population indices. About MARK, I’m working with it to answer some other questions I have, but I think if I estimate population abundance with the Robust Design, for instance, it will also be affected by the sampling effort. 

Is currently already use PIT tag in  Microchiroptera.

Alexey, thank you very much for an useful information.

ZČ

As mentioned before, drop off mechanisms are not 100% reliable.

When I was working on large mammal telemetry, we used pure cotton straps and integrate it into the collar's belt (additional to drop off mechanism) - just to make sure that the collar will get off the animal. Cotton will deteriorate depending on weather conditions. We used a Swedish "recipe" in Slovenia and it worked perfectly (we have similar moderate climate). For one year study period on an infant bear or deer we used one strap of 4 cm wide cotton, for adult female 2, and for adult male 3 straps.

I would agree with Owen. The hedgehogs may not be effected by being albino since they seem to go about their business without much real concern for predation. That spiked armor they have. Other small mammals such as mice and rabbits have a distinct disadvantage with albinism. They are primarily prey and without the ability to blend in they do not survive long in the wild.

It would be terribly interesting to follow your two hedgehogs and see if they find mates and produce any offspring. Also to see if their parent produces more albinos in subsequent litters.

view: "Restraint stress in biobehavioral research: Recent developments" (Tatyana Buynitsky, David I. Mostofsky)

I think it is ok to to use this method untill or unless they are not scare away by light

Mmmm. Partially, I am against killing animal for just counting them when so many Museums and Institutions have specimens in ancient collections. Maybe with live traps I can stand for. Searching...searching for the animal's paths is also a problem! Owls, other birds of prey and small carnivores are excellent in getting small prey samples! It is more work (see the book of Andrews 1990 or Arrizabalaga i Blanch et al 1986)

From the look of the signal, it should be easy to approach this problem in any of several different ways. You could load the file into any data analysis environment, detect spikes above a threshold value, time the interval between spikes, and write mean values to a separate data vector or text file. Automating this process is straightforward in almost any advanced data analysis environment. Or you could go the analog route. You can trigger a monostable multivibrator from the spikes, and then integrate the output of the multivibrator using a low pass filter to create an analog voltage proportional to the frequency of the spikes. You can then record that analog voltage with any data acquisition system.

In addition (and related) to ambient noise level how about other environmental factors such as air turbidity, humidity, precipitation? Perhaps obvious but not really mentioned above. Also, the animal's endogenous state is important to recognize such as motivation level in relation to, say, hormone levels cued by exogenous factors like proximity of a rival or mate, etc.

I used 5l buckets as pitfall traps for shrews. As I was catching shrews in Western Europe, I dug a whole to put the bucket below ground level into the ground, the put a second bucket, which had some (small holes drilled into the bottom) into the first bucket, so it would be flush with the soil. This way, the water would drain from the pitfall, should it rain. I also added mealworms (and sardines) as food into the traps. Dry cat food should also work.

I also added some wood shavings (i.e. hamsterbedding into the traps).

As shrews are active throughout the 24-hour period, and have a very high metabolic rate, traps should be visited every 2-4 hours to avoid unnecessary casualties.