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Index

Introduction......................................................................................... 1

Module start up.................................................................................... 2 1 Input................................................................................................. 4

2 Input pellet batch data...................................................................... 5 3 Input results of analysis ................................................................... 7

4 Interrupt input................................................................................ 10 5 Continue input ................................................................................ 10

6 Input completed.............................................................................. 11 7 Inquiries ......................................................................................... 21

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Manual Owl Pellet Analysis

Introduction

Owls are birds of prey which regurgitate what their stomachs cannot digest.

The pellets they produce enable us to dissect and attempt to identify the types of mouse skulls contained in this undigested food. The analysis of these pellets

teaches us something about the feeding habits of owls, and the results are also used to produce mammal atlases. The examination of owl pellets is carried out

all over the world, and the techniques for doing so are taught every year on

winter nights, with enthusiasts analysing pellets together in groups. Unfortunately, much of the data produced is lost because it does not always

find its way to a central data bank. Indeed, since the collector of a pellet is not usually the person who examines it, there is also a lack of feedback from the

latter to the former. We want to try to put this right by creating an online module for the registration of the results of owl pellet analyses.

The advantages of such an approach are: � The centralisation of data in a database � The use of uniform, detailed analytical techniques � The automatic feedback of results to the collectors of pellets if these individuals are known and have provided an email address.

There are currently two elements to the module: � The process of inputting data � The facility to make inquiries about results An individual must sign in to the database to input data, and has to be

registered before being able to do so. Registration takes place on the first

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occasion someone clicks on the option to 'input' data.

There is, however, no requirement to sign in to request information. Indeed, a

collector can request data from the online database by using the information received by email from the analyser of the pellets.

Module start up

The online registration of owl pellets can be conducted on the www.owlpelletanalysis.com website.

Some tips for a smooth data entry process are set out below:

Key data you will need to include:

� Name of the collector � Municipality where the pellets were found � Location where the pellets were found (church-yard, willow tree...) � Date when the pellets were collected � Predator � Origin if known (nest, roost site) � Total number of pellets � Project you are working for: Barn Owl working group, mammal working group, individual interest group...

� Analysis method (i.e. all pellets are lumped together or individual pellets)

So, how do you determine the appropriate method of analysis for your pellets before you begin?

What is the status of the pellets you want to dissect? � Entire pellets: make a record of the elements found in each pellet (upper jaw/maxilla, left lower jaw/mandible, right lower jaw/mandible) and then select input per pellet

� Entire pellets and loose fragments (debris): for each pellet create a record of the elements found therein as well as a list of the debris. Then, select the

input per pellet option, and when the data relating to the final, complete pellet has been entered, you will also have the opportunity to input the

details of the pellet debris.

� More loose fragments than pellets (i.e. the pellets have fallen apart): register the debris by species before selecting the input by numbers option.

� Only loose fragments: create a record of the species contained therein and the numbers thereof and then select the input by numbers option.

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�

Entire pellets Entire pellets and loose

fragments

More loose fragments

than pellets

Only loose fragments

Analysis Analysis per

pellet

Analysis per

pellet and loose

fragments separately

Analysis per

pellet and loose

fragments separately

Analysis of

loose fragments

Create a record for

each pellet, including the

species and the number of

elements

Notation Create a record for

each pellet, including the

species and the number of

elements

Record in a

separate list the species

and the numbers

thereof for the loose

fragments

Create a record of the

species and the numbers

thereof

Create a record of the

species and the numbers

thereof

Select input

method: input per pellet

Online

registration

Select input

method: input per pellet

After entering the data for

the final pellet, you can

then input the details of the

elements found in any

loose fragments

Select input

method: input by numbers

Select input

method: input by numbers

Analysis All methods of analysis

available

All methods of analysis

available

A limited form of analysis is

available

A limited form analysis is

available

Enter the number of undigested pellets in the module’s 'pellet entry form'. Specify the method of analysis depending on the approach used:

� I only have the numbers of the prey species found in the pellets: Select input by numbers and then enter the results. If you enter the details of

more than 50 prey species, you will get an indication of which ones are linked

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to the staple food.

� I have detailed information about upper jaws/maxillas and lower

jaws/mandibles per pellet: Select input per pellet and enter the results. If you have entered the details of

more than 50 species of prey, you will get an indication of which of them are linked to the staple food. After entering the data relating to the final pellet, you

will be asked whether you have information about other pellets to record. If you do not, you can enter the details of the remaining elements found in the

debris. Although this data is not included in the analysis, it may still be important for mammal monitoring purposes, e.g. you may find the remains of

a Fat Dormouse in the debris, but not in the examined pellets.

1 Input

You must sign in to the website whenever you want to input data. The first

time you do this you will be asked to register.

To register, select the 'Register' button.

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Some basic information will be required when you register: � First name � Last name � Street name and number � Village/town � Country (drop-down list) � Email address � Telephone/GSM � Username

The municipality option provides you with a drop-down list of municipalities

and postal codes. You can accelerate the municipality search by entering the first letter of the relevant area.

An email address is needed for you to receive your password, while a phone or cell phone (GSM) number can be useful when certain data is unclear and

requires clarification. The username is a unique name which is linked to you; it can be your own

name if you prefer. All of these fields are obligatory.

When you click on 'Register' you will be returned to the sign in screen where

you will be assigned a code. You will also receive this code/password by email. You should save this email so that you can refer back to it if you forget your

username and code/password at some point in the future.

If you have forgotten and/or enter an incorrect code/password, a link will

appear which enables you to retrieve this information. You will be asked for the email address with which you registered on the site, hence the importance of

providing this information carefully.

2. Input pellet batch data

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Select from activities: Pellet analysis input

You must first enter information about a batch of pellets before moving on to record the results of the analysis thereof.

This information is divided into the following categories:

� Data collector � Data analyser � Data location � Pellet data � Project specification � Analysis method

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By default, the analyser’s data is copied from your registration data and can be

modified.

The collector's data can be copied from the analyser’s data if you are also the collector; if this is the case, just check the tick box.

If the collector is not the analyser, enter the collector's data here. You also have the option to enter the collector's email address. The collector will then

receive notification when all of the information concerning this particular batch of pellets has been recorded.

So far as the location is concerned, the focus is on the address of the site and a description (nature) of it. By default, some choices are automatically

presented, but this is a field where you can also enter your own description by clicking on the final option: 'Add'. If you know them, you can also enter the

UTM codes of the location. The following information should be entered about the pellets:

� Collection date � Predator � Origin � Date of analysis � Total number of pellets � Estimated age There is a choice of nesting place, roosting place or unknown for the origin

category, while the number of pellets is the total number of entire, undamaged pellets you have analysed.

If you are involved in a pellet analysis project, you can refer to this in the

project specification option. The following options are currently available: � Individual � Education: school � Education: analysis course � Unknown

There are two methods of analysis:

� Input per pellet � Input by numbers Depending on the method of analysis chosen, you will be presented with

different input screens. You can always return to the input information relating to the pellet batch, but you will not be able to change the analysis method

once you have started entering the data. So, be sure to make the right choice here before you save your findings.

3 Input the results of the analysis

The analytical tool chosen leads to the display of different input methods, but the structure of the input screen always remains the same. In the centre of the

screen is the space to enter the details of the prey species found in the pellet, along with the number of individuals thereof and the number of elements

found (maxilla, mandibles). On the right side of the screen is the complete list of species of prey with the details of their numbers, while at the bottom of the

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page an initial view of the analysis of the data you have entered is already set

out:

� the value of the staple food � the average food weight per pellet, shown in grams of prey animal � the prey animal index � the average prey weight

Input form with prey species totals - Input form with skull fragments per pellet

For each selected prey species, the details of the number of individuals found

can be provided. There is also the opportunity to add a comment if you deem it to be necessary.

Input by numbers of prey

Here, the analysis of the pellets is not recorded per pellet. The lists for the inputting of this data are available through the following link:

http://www.owlpelletanalysis.com/files/pellet form totals.xls.

The results of the analysis are summarised per species of prey found, but there is no detailed information per pellet. This means that there is a lack of data

and we are unable to conduct all possible analyses. A limited form of analysis will, however, be available. Two buttons are not presented on this input screen:

the pellet ratio and the individual index. The data is instead entered by following the species list and inputting the

details of the numbers of prey found. If you click the enter button too soon, you will see the following message:

When the input list on the right side of the screen is complete, you can save your data by pressing the 'Entry complete?' button. You will be asked for

confirmation that this list is correct.

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If your answer is no, you can continue to enter your data. If your answer is yes, the input buttons are disabled and you can only use the buttons from the

overview list on the right of the screen. You can switch between displaying totals and percentages here. If the details of more than 50 animals of prey

have been entered, the species which fulfil the staple food criteria will appear in bold type.

Input per pellet

We do have detailed information available per pellet here. The lists for this

data are available through the following link: http://www.owlpelletanalysis.com/files/pellet form details.xls.

The inputting of data is performed by following the species list and entering the details of the number of elements of prey found (maxilla, left and right

mandible). The counters go up to a maximum of 10. If you press on the 'input' icon too soon, without selecting a species and/or element, you will get the

following reminder:

When the input list on the right of the screen is complete with your notations for this particular pellet, you can save the data by pressing the 'Pellet

complete?' link. You will be asked for confirmation that the list is correct.

If your answer is no, you can continue to enter your data. If your answer is yes, the counters move on to the next pellet. On the right of the screen you

will see an overview of the details of the pellets already entered, with the species listed per their percentage rate in relation to the total. You will find the

analysis of the following items at the bottom of the screen:

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� the determination of the staple food � the average food weight per pellet in grams of prey animal weight � the average prey weight � the prey animal index When the details of more than 50 prey animals have been entered, the species which are linked to the staple food are set out in bold type on the right side of

the screen. When you have finished entering the data relating to the final pellet, a

message that you have done so according to the number of pellets specified in the original pellet batch data will be displayed.

If this is correct, it should be confirmed by pressing the yes button. You will then be returned to the pellet batch information with the following message:

If you have not entered the final piece of information, you can respond in the negative in order to continue inputting your data. If, however, you have indeed

entered the details of the final pellet and confirm this, you will be asked whether you want to enter information about loose debris. If the answer is yes,

you will be prompted to provide details of all of the remaining species with

their elements. These residual data are stored in the central database for later use, but are not included in the analyses. When there is a lot of debris (more

than the limit of 10 per element), it is better to enter these details separately using the input by numbers method with the same pellet batch information.

4 Interruption of input

You do not have to enter all of your findings in one go. You can enter your data in stages after pressing the 'pellet complete' button when entering per pellet or

after clicking the 'input' button when entering your information by the numbers of prey method. You can then exit the application without any loss of data.

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5 Continue input

When you have interrupted your entry of data and want to complete the task later on, you can do so after signing in by selecting the option: 'Continue

input'.

Here, you will be given an overview of the details of the pellet batches you have entered into the system and those that are still open. You can sort this

table by clicking on the column of your choosing. The table provides the following data: predator, municipality and address of the

origin of the pellets, description, collection date, total number of pellets, and analysed pellets.

After making your choice, you will be returned to the input module where the most recent status will be displayed.

6 Input completed

When the entry of data is complete, the button changes from the 'adapt data

entry' to a 'graphics' option, where you can continue to a graphical representation of the results. Here, more detail is provided by bar charts of the

distribution of species, frequency tables of the pellet weight classes, tables of individual indices and pellet ratios, and triangular diagrams of the most

significant distributions, which provide more detailed information about the results. Some representations give you the opportunity to weigh your data

against a self-selected spatial scale according to the geographical area your

pellet batch relates to.

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When you switch to another form of representation, the pointer will move to the new values thereof. In this way you can keep track of the internal

movement of locations within the chosen region.

So, which forms of representation are available and how should you interpret

them?

There are three types of data representation available: bar charts; scatter

plots; and triangular diagrams.

Bar charts

Distribution of prey animals

This is a bar chart representation of the results as a percentage of the pellet batch. You can view your data against the historical data of the region that

your location belongs to. The chart specifies how many locations make up this historical, regional data (these are only locations with the pellet data of more

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than 50 animals of prey).

This will give you an idea of how your results differ from the historical data of

the region.

Pellet ratio and individual index per prey species

The pellet ratio and individual index reveal the extent to which your results are divided between the pellets. This form of representation is, however, only

visible if you have entered your data per pellet. The pellet ratio is always

smaller than one and the individual index is always greater than or equal to one. Hence, both can be put into a single representation of the data. Along

with the prey index, these are the parameters used for determining the staple food. They can also be presented individually as staple food parameters. In this

circumstance, the norms are an individual index of more than 1.5 for the species which constitute the staple food, and more than 0.33 for the pellet

ratio. No attention was paid to these indices in the past, but by collecting them now we are able to check these regional data against each other.

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Frequency of the number of prey per pellet This is an indication of the hunting intensity of the Barn Owl. The more small

prey it catches, the more prey animals will be present in a pellet. This representation is only visible if you have input your data per pellet.

Food classes Food classes represent the total prey weights per pellet and their frequency in

pre-established weight classes. This form of representation is only available when you have entered your data per pellet. If there is a clear indication of the

presence of numerous pellets which are less than 80 grams in weight, it may be that these originate from young chicks, while an indication of numerous

pellets above 100 grams means that these are probably from older chicks. When a clock diagram like the one below is displayed, the pellets probably

originate from adult birds.

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Scatter plots

You can hover your mouse over a red dot in the scatter plots to discover what

historical data are linked to it.

Relationship between the number of prey animals and the number of

prey species

The more you analyse, the more species you will find. This may be a matter of logic, but what is surprising is that there is a law of physics that I will call the

Da Vinci code of the owl pellet. This may seem far-fetched, but the rule which determines the number of seeds in a sunflower head, the position of a leaf on

a stem, or the number of rabbits in a certain generation, can also apply to owl

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pellets. The rule states that, on average, for every extra species one wants to

identify, one has to follow the Fibonacci sequence. For the first species there is

one prey animal, for the second there is one extra prey animal, for the third there are two more animals, for the fourth three more animals, for the fifth

species five more animals, for the sixth species eight more animals, for the seventh species 13 more animals, for the eighth species 21 more animals, for

the ninth species 24 more animals, for the tenth species 55 more animals, for the eleventh species 89 more animals, and for the twelfth species 144 more

animals, etc. This rule relates to the average pellet analysis of 560 pellet analyses in Flanders. What is interesting is that we can set out the biodiversity

in the feeding menu. If there are more species than the Fibonacci numbers indicate, this dot in the graph will appear above the average curve, and when

there are fewer species than the Fibonacci sequence indicates, the dot will appear below the curve. Dots below the curve indicate specialisation in the

menu of one or more species, while dots above the curve reveal a greater diversity. A greater diversity of species in the composition of the food implies a

greater biodiversity.

Relationship between the proportion of small prey species (<20 gram) and average prey weight

There is a linear relationship between the two parameters. The average prey

weight decreases as the proportion of the presence of small prey animals

increases. In some regions of Flanders, the dots are on a clear line which runs from 0% of small mice and an average of 30 grams prey weight, to 100% of

small mice and an average of 10 grams prey weight (mainly shrews). The scattering of dots on this line and our own entry of data tell us something

about the quality of the food composition. The more to the left the dot is, the better the food quality; the more to the right the dot is, the lower the food

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quality and the more prey the predator will have to catch. Nevertheless, this

does not mean that the owl will be worse off; it may be, for example, that

there is an excessive supply of shrews.

Triangular diagrams

The first two are well known tools, but the latter require some additional explanation.

The distribution and grouping of micro-mammalia on the website lends itself perfectly to the use of triangular diagrams. Such diagrams can represent three

variables in a graphical form on the basis that the third variable can be defined as being derived from its two counterparts. This is achieved by regarding the

three variables as one entity. The third variable is always equal to the total

minus the other two variables, and the variables are represented as a proportion of this total. The order of the variables is immaterial. This is

because a triangular diagram makes use of the proposition that the sum of the angles of a triangle always equals 180°.

The prey Families are made up of three large families of mammals, (Shrews (A), Voles (B) and True Mice (C)), and can be represented as a triangular

diagram of these three groups. A summary is then produced of these three families, but not of all of the species found. By default, an equilateral triangle

is used, with the horizontal edge at the bottom. The three axes of the variables are the sides, which range from nought to 100. On the lower side, from left to

right, is (A), while the right side, from the bottom upwards, is (B), and the left side, from the top downwards, is (C). A set of variables is plotted by reading

the first variable along the bottom edge and the second variable along the right hand side. This always goes in a clockwise direction. If we now draw a

parallel line through the respective values of these two variables on the axis (A

and B) that is parallel to the side going on to the axis (C and A), we can then read the value which automatically equals our third variable by drawing a

parallel with B through the intersection of both of these parallels.

There are two main prey species in each family (Common Shrew and Greater White-toothed Shrew for the Shrews; Field Vole and Common Vole or European

Pine Vole for the Voles; and Wood Mouse and House Mouse for the True Mice). This means that we can also establish a triangular diagram for each of the

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families separately from the main prey, with the other species from the

respective family as a third variable. Once a collection can be split into three

components which together form an entity, they can be represented in a triangular diagram. In each case it is important to describe how you compose

your three variables. In our previous example we have the Common Shrew on the A-axis, the Greater Shrew on the B-axis and other Shrews on the C-axis.

Triangular diagrams can be read as follows: when we draw a diagonal line from one corner of the triangle to its opposite side, then the points to the left of this

line are subject to the following rule: the value of the variable in the opposite axis is greater than the value in the axis on the right side of the diagonal. The

points on the right of this diagonal are subject to the following rule: the value of the variable on the opposite axis is smaller than the value on the right axis

of the diagonal. The points on the diagonal have a value on the opposite axis that is equal to the right axis of the diagonal. The closer the points are to the

centre of the triangle, the more equally the variables are divided. When the values are driven more towards one of the points of the triangle, then the

variable on the right side of that point is the most significant.

It is also possible to hover your mouse over the red dots in the triangular diagrams to discover the origins of the historical data.

Distribution by biomass The three parameters we use here are small prey animals (<20 grams), large prey animals (>40 grams) and others (mainly 25-30 grams).

Distribution by habitat For this representation of data the species are grouped together according to

their main habitat. We concentrate the choice of habitat on the three types

that are typical for the Barn Owl, namely: � Grassland: Common Shrew, Crowned Shrew, Bi-coloured Shrew, Common Vole, Bat, and others

� Bush: Water Shrew, Pygmy Shrew, Bank Vole, Water Vole, Pine Vole, Field

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Vole, Harvest Mouse, Wood Mouse, Garden Dormouse, and Frog

� Inhabited: other prey species. We have established that the share of the 'Bush' habitat is usually larger than that of 'Grassland'. Most of the collections of dots are on the bottom left of the

representation, while the share of 'Grassland' increases at the expense of the 'Inhabited' category.

Distribution of the small mammal families

Distribution of the main species of True Mice

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Distribution of the main species of Voles

Distribution of the main species of Shrews

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7 Inquiries

This section of the website allows you to request information for free about

different municipalities. If data exists for a particular municipality, it will be

displayed relative to the historical regional data to which this location belongs. If, however, no historical data for the municipality exists, only the historical

regional data to which the municipality belongs will be displayed.

If you, as a pellet collector, have provided your email address to the analyser, you will automatically receive a variety of data when the analyst has entered

his findings, namely:

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� Name of the analyst � Name of the municipality where the pellets were found � Predator � Total number of pellets � Validation code

Enter these data into the input form and then click on 'Next' to see the details.

You cannot change this form; it is only available for review. Click on 'Next' to

obtain the analysis.

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The lower and right side sections are important here. Some of the properties

and characteristics of the analysed pellet batch are set out below:

� Staple food criteria and result; the species which fulfil the criteria are set out in bold type on the right

� Prey animal index. This is the number of prey animals divided by the number of pellets

� Average food weight per pellet � Average prey weight.

On the right is a list of the species found with the following details, depending

on your choice of button: � Pellet ratio: the percentage share of the pellets in which the species was found

� Individual index: the average number of animals of this species found in the pellets in which the species was found

� Totals: the absolute totals � Percentages: percentage distribution of the species among all prey animals found

The 'Graphics' button takes you to the graphical analysis of the results. These are discussed in Chapter 6 (Input Completed)

Comments and feedback are welcome at the address of info@owlpelletanalysis.com