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The dive analysis


MT-Dive scans the recorded depth data and searches dive events according to the 'Parameters for the dive analysis' (see below) set by the user. MT-Dive features:

  • Searching onset and ending of the dive, identification of the bottom phase by various methods.
  • Wiggles = Diving up and down with relatively small amplitudes during the bottom phase. Thus a zig-zag-shaped bottom phase is an indicator for hunting. Export of the wiggles into a separate result file.
  • Search of dive stops (Interruptions at the ascent or descent phase).
  • Frequency distribution (e.g. time spent between 0 and 2 meters, between 2 and 4 meters, and so on)
  • Water temperature analysis: Mean temp. of dive and bottom phase, min. and max temp, temp. at max depth
  • Creation of images (JPEG) of every found dive event
  • If speed data are available: Calculation of dive angles, travelled distances. Presentation of dive profile as way-way diagram.
  • If positions (latitudes, longitudes) are available: Calculation of direct distances and travelled distances e.g. at surface.
  • Identification of U, V, W, Y and parabola-shaped bottom phases

U-shape V-shape W-shape Y-shape Parabola shaped

My-MT is available now! By means of My-MT you can write your own dive analysis procedures. My-MT provides the basic modules of MT to visualize and process the data and to find dive events. You can replace or extend the dive analysis of MT by your own analysis procedures.
All you need is basic knowledge about DLL programming. No knowledge about Windows programming required, no knowledge about object oriented programming required. We provide you with a simple example how to create such a DLL.

MT-Dive visualizes the found dive event. Then the user can correct each of the MT-proposals (e.g. end-of-dive). The user can accept or reject the entire event. If the user accepts the event then MT-Dive analyzes the current event and exports the results into a text file (each event into one line):

# Nr of event
Pause Interval to preceeding dive event. Surface time.
Onset Onset of the event as hh:mm:ss
Dive shape U,V,W,Y, Parabola shape
Duration Duration of the event [sec]
Onset bottom Pause between events [sec]
Dur. desc Duration of descent diving [sec]
Dur. bott Duration of bottom diving [sec]
Dur asc. Duration of asscent diving [sec]
VV down Vertical velocity at the descent phase [m/sec]
VV bottom Vertical velocity at the bottom phase [m/sec]
VV up Vertical velocity at the ascent phase [m/sec]
Max depth Maximal depth of the event [m]
Min depth Minimal depth at the bottom phase [m]
Mean depth Mean depth at the bottom phase [m]
Integral Integral of the entire dive [m*sec]
Median depth Median depth at the bottom phase [m]
Sum way vert. Total vertical way at the bottom phase [m]
SD Standard deviation at the bottom phase [m]
Diving Efficiency Bottom time / (Surface time + Dive duration)
Broadness Index Bottom duration/Dive duration
Depth Range Index Range in depth of the bottom phase/maximum depth
Symmetry Index Time of the bottom phase when max. depth is reached / bottom
Mean Vert. Acceleration Sum abs(vertical acceleration) / Nr values at bottom phase
Mean depth Mean of the depth values of the entire dive event
Frequ. distribution # data points at depth bands (up to 30 bands). Optional
Water temperatures Mean temp. at dive, mean temp at bottom, min. and max temp. at
bottom, temperature at max depth. Optional.
Diff. dive duration Difference to preceding dive duration [sec]
Diff. max depth Difference to preceding max depth [m]
Wiggle analysis
Mean amplitude zigs Mean amplitude of wiggles up [m]
Std. deviation zigs Stand. dev. of the amplitudes of the wiggles up [m]
Median zigs Median ampl. of the wiggles up [m]
Mean amplitude zags Mean amplitude of wiggles down [m]
Std. deviation zags Stand. dev. of the amplitudes of the wiggles down [m]
Median zags Median ampl. of the wiggles down [m]
Sum amplitudes Sum of abs(Wiggle amplitudes)
Wiggles onset Date and time of first wiggle
Wiggles ending Date and time of last wiggle
Duration Duration of the entire wiggle interval
Depth at first Recorded depth at the first wiggle
Depth at last Recorded depth at the last wiggle
Depth min. of all Recorded min. depth at the wiggle interval
Depth max of all Recorded max. depth at the wiggle interval
Angles and dsitances (if speed data avialbale)
Angle down Dive angle at the descent phsase [m]
Angle up Dive angle at the ascent phsase [m]
Dist. down Distance travelled at the descent phase [m]
Dist. bottom Distance travelled at the bottom phase [m]
Dist. up Distance travelled at the ascent phase [m]
Dist. proj surface Length of the route projected to the water surface.
Dive stop analysis. Up to 8 entries for the descent and the ascent phase.
Onset Onset of the dive stop relative to the event onset [sec]
Duration Duration of the dive stop [m]
Depth Recorded depth at the dive stop [m]
Vertical Velocity Dive gradient immediately before the dive stop [m/sec]
Extended analysis. Up to six additional entries, user defined. See below.

List of dive characteristics calculated and exported by MT-Dive. Water temperatures and dive frequencies (Frequ. Distribution) will be included if these features are enabled by the user. This list can be extended by entries according to user wishes. (E.g. Average magnitude in channel X at the bottom phase’). Please inquire in case you have special wishes.

Then MT-Dive searches the next event, analyzes it ...and so on.There is also an 'automatic mode'. In this mode the user selects a section of the channel (e.g. the entire channel), then MT rapidly scans the entire section for dive events, analyzes each event and exports the results. This is a very fast method. Disadvantage: the user cannot check and - if necessary - correct single events.

The user can select from 4 modes how to detect the
bottom phase.

  • Normal The criteria for what constitutes a 'bottom phase' in a dive are based around looking for a point of inflection in the depth profile. Dives with a clear bottom phase in them consist of a descent phase (with usually constant rates of descent), followed by a point of inflection where the animal flattens out (although it may continue down slightly or even rise). This basic second trajectory is then followed for a while before a second point of inflection is followed by an ascent to the surface which marks the end of the bottom phase. Of note are parabolic dives, which have no point of inflection (and are, by definition, therefore not U-shaped dives anyway) and, of course, V-shaped dives where the point of inflection results in a phase which takes the bird back to the surface.
  • AnDive Because of compatibility to the DOS program 'AnDive' there is this mode.
  • Fix Bottom The bottom is set fix to a certain level e.g. 70 percent of the max dive depth.
  • Wiggle defined This method defines the bottom according to Halsey ("A thorough and quantified method for classifying seabird diving behaviour", Springer2007). The bottom phase is defined as starting with the start of the first wiggle that occurs deeper than the ledge and ending with the end of the last wiggle that finishes deeper than the ledge. The ledge is a user defined threshold e.g. 75 percent of the max depth of the current dive.

The parameters for the dive analysis

The user can specify up to 6 additional characteristics, to be combined freely. Examples : Calculate the maximum value of the third channel (e.g. recorded heart rate values) during the bottom phase.
Calculate the travelled distance at surface (between two consecutive dives).

Analysis of Dive Bouts

MT-Dive also can find and analyze dive bouts (series of dives). The following bout characteristics will be calculated and exported into a result file:

Count Serial number of current bout
BoutOnset Date and time
Nr Dives Amount of dives of current bout
Nr V-dives Amount of V shaped dives
Nr U-dives Amount of U shaped dives
Nr W-dives Amount of W shaped dives
Nr Y-dives Amount of Y shaped dives
Nr parabola dives Amount of parabola shaped dives
FrquDives Dive frequency. NrDives/DurationBout [1/h]
DurationBout Duration of bout [sec]
TimeSpentBottom Total bottom time [sec]
TSB/DurBout (Total bottom time) / (Duration of bout)
MaxDuration Longest dive [sec]
AvgDuration Average duration of all dives [sec]
MaxDepth Greatest depth al all dive events [m]
AvgMaxDepth Average of max depths of all dives [m]
MeanDepth Average depths of all dives (without surface) [m]
MeanBottom Average depth of all bottom phases [m]
TotDiveTime Total time spent diving [sec]
Integral Integral of all dives [m*h]
Int/DurBout Integral/Duration bout [m]
Diving Efficiency (Total bott. time) /(Surface time + Total dive time)
AvgDepth V-Dives Average depth of all V-shaped dives [m]
MaxDepth V-Dives Max. depth of all V-shaped dives [m]
AvgDepth non V-Dives Average depth of all dives with bottom phase [m]
MaxDepth non V-Dives Max. depth of all dives ith bottom phase [m]
MeanROD (all points) Average of all ‘Rate of Descents’ [m/sec]
Average RODs Average of all grad. of all descent phases [m/sec]
MeanROA (all points) Average of all ‘Rate of Ascents’ [m/sec]
Average ROAs Average of all grad. of all descent phases [m/sec]
Nr Wiggles Amount of wiggles of all dives
Nr DiveStops Amount of Dive stops of all dives
way-way diagram

If speed data are available then MT can create a way-way diagram of the dive profile.
The unit of both axes are meters, hence this diagram shows the route of the animal.


MultiTrace-manual As word file (MTDive.doc, 500 kBytes)
MultiTrace-demo A demo version of MT-Dive for Windows without the possibility to export results (setup.exe, 470 kBytes)

View manual of MT-Dive (opens in separate window)

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