Most of the penguins are now moulting so no logger deployments are taking place.  On the mainland, Kate Robinson is analysing the Robben Island dive data with a program called MTDive.

Photo taken in November, the penguin you can see in the middle with fluffy looking feathers on its back is moulting.

What does the logger data look like?

The data inside the logger is stored as binomial data when we download the data to a computer it is converted into text files.


Examples of the text files:
Here is part of the GPS data text file from Deployment no.7. The logger was programmed to take a GPS position every minute that the logger received data from 3 or more satellites. When the logger could not find satellites we programmed it to stop searching for 10 minutes to save battery.

************* GPS DATA *************
Device Number .............: 00272 / v7.4a 091006
Datasets Stored ...........: 1587
Logger Programmed .........: 19.05.2011 13:40:18
Logger Started ............: 20.05.2011 05:00:00
Sampling Interval .........: 001 min / 00 sec
Required Number Of Sats ...: 3
Search Limit ..............: Yes
 Max. Allowed Search-time .: 003 min
 Off-time .................: 010 min
Pressure Control Enabled ..: Yes
Pressure mode .............: Upon Each Surfacing
Activity Interval .........: No
************************************
20.05.2011 05:00:32 33.7956333 S 018.3731400 E 02.9 000.3
20.05.2011 05:01:36 33.7956900 S 018.3732733 E 03.0 001.1
20.05.2011 05:02:40 33.7958767 S 018.3739017 E 03.0 000.6
20.05.2011 05:03:42 33.7960083 S 018.3735600 E 02.5 002.4
20.05.2011 05:04:44 33.7952617 S 018.3726200 E 02.7 002.2
20.05.2011 05:05:46 33.7939800 S 018.3717400 E 03.2 002.4
20.05.2011 05:06:48 33.7956117 S 018.3732233 E 03.5 000.0
20.05.2011 05:07:52 33.7955833 S 018.3732067 E 04.5 003.4
20.05.2011 05:08:56 33.7956750 S 018.3732100 E 02.0 000.4
20.05.2011 05:10:00 33.7958617 S 018.3737567 E 02.0 000.4
20.05.2011 05:11:02 33.7953433 S 018.3728717 E 02.9 001.8
20.05.2011 05:12:04 33.7948583 S 018.3724250 E 02.9 006.0
20.05.2011 05:13:05 33.7956283 S 018.3731517 E 04.5 000.0
20.05.2011 05:14:06 33.7955267 S 018.3730350 E 02.2 001.2
20.05.2011 05:15:09 33.7957750 S 018.3731033 E 07.9 000.8
20.05.2011 05:16:11 33.7957033 S 018.3725100 E 01.8 000.6
20.05.2011 05:17:15 33.7955900 S 018.3730750 E 01.6 000.0
20.05.2011 05:18:19 33.7954900 S 018.3724250 E 04.5 001.7
20.05.2011 05:19:23 33.7955467 S 018.3729233 E 01.6 000.4
20.05.2011 05:20:27 33.7954050 S 018.3724983 E 05.4 000.4
20.05.2011 05:21:31 33.7957650 S 018.3734867 E 01.6 000.4
20.05.2011 05:22:35 33.7952200 S 018.3720750 E 01.6 000.6
20.05.2011 05:23:39 33.7956250 S 018.3730867 E 01.8 000.1
20.05.2011 05:24:41 33.7957100 S 018.3733867 E 02.2 000.3
20.05.2011 05:25:45 33.7955117 S 018.3728000 E 01.6 000.5
20.05.2011 05:26:49 33.7957000 S 018.3733100 E 01.6 000.4
20.05.2011 05:27:51 33.7957233 S 018.3725700 E 01.6 000.0
20.05.2011 05:28:53 33.7952433 S 018.3732950 E 01.8 000.0
20.05.2011 05:29:57 33.7957133 S 018.3734900 E 02.5 000.3
20.05.2011 05:31:01 33.7956550 S 018.3730233 E 01.6 000.2
20.05.2011 05:32:04 33.7965967 S 018.3752050 E 01.8 000.1
20.05.2011 05:33:06 33.7959417 S 018.3732117 E 06.3 009.8
20.05.2011 05:34:08 33.7957667 S 018.3730050 E 02.4 002.5
20.05.2011 05:35:12 33.7955500 S 018.3728267 E 02.4 000.5
20.05.2011 05:36:14 33.7947717 S 018.3729350 E 02.4 008.1
20.05.2011 05:37:18 33.7953583 S 018.3750867 E 03.0 000.5


There is also a text file for the temperature and pressure data taken every second. At the top it tells you the logger device number, how many datasets the logger recorded, when it was programmed, when it did started, sampling intervals and what the sensos were. The date is the first column, the time the second column, temperature in degrees Celsius is the third column and the pressure is in the fourth column.
 Here is part of the Sensor data text file from deployment no.7:

************* SENSOR DATA *************
Device Number .............: 00272 / v7.4a 091006
Datasets stored ...........: 107917
Logger programmed .........: 19.05.2011 13:40:18
Logger started ............: 20.05.2011 05:00:00
Sampling Interval .........: 00 min / 01 sec
Number of sensors .........: 2
Sensor in column [1] ......: TempExt
Sensor in column [2] ......: Pressure
***************************************
20.05.2011 05:00:00    7.342       0.021 
20.05.2011 05:00:01    7.337       0.017 
20.05.2011 05:00:02    7.337       0.017 
20.05.2011 05:00:03    7.327       0.017 
20.05.2011 05:00:04    7.318       0.021 
20.05.2011 05:00:05    7.318       0.017 
20.05.2011 05:00:06    7.308       0.021 
20.05.2011 05:00:07    7.298       0.021 
20.05.2011 05:00:08    7.279       0.017 
20.05.2011 05:00:09    7.274       0.017 
20.05.2011 05:00:10    7.265       0.013 
20.05.2011 05:00:11    7.250       0.017 
20.05.2011 05:00:12    7.231       0.017 
20.05.2011 05:00:13    7.207       0.017 
20.05.2011 05:00:14    7.183       0.021 
20.05.2011 05:00:15    7.164       0.017 
20.05.2011 05:00:16    7.131       0.017 
20.05.2011 05:00:17    7.116       0.017 
20.05.2011 05:00:18    7.083       0.021 
20.05.2011 05:00:19    7.078       0.013 
20.05.2011 05:00:20    7.073       0.017 
20.05.2011 05:00:21    7.068       0.017 
20.05.2011 05:00:22    7.063       0.017 
20.05.2011 05:00:23    7.054       0.021 
20.05.2011 05:00:24    7.044       0.013 
20.05.2011 05:00:25    7.054       0.017 
20.05.2011 05:00:26    7.035       0.021 
20.05.2011 05:00:27    7.025       0.017 
20.05.2011 05:00:28    7.011       0.017 
20.05.2011 05:00:29    7.001       0.017 
20.05.2011 05:00:30    6.982       0.017 
20.05.2011 05:00:31    6.963       0.017 
20.05.2011 05:00:32    6.948       0.013 
20.05.2011 05:00:33    6.939       0.017 
20.05.2011 05:00:34    6.920       0.021 
20.05.2011 05:00:35    6.900       0.017 
20.05.2011 05:00:36    6.886       0.017 
20.05.2011 05:00:37    6.872       0.017 
20.05.2011 05:00:38    6.867       0.013 
20.05.2011 05:00:39    6.857       0.013 
20.05.2011 05:00:40    6.857       0.021 
20.05.2011 05:00:41    6.838       0.017 
20.05.2011 05:00:42    6.843       0.017 
20.05.2011 05:00:43    6.843       0.017 
20.05.2011 05:00:44    6.843       0.021 
20.05.2011 05:00:45    6.843       0.017 
20.05.2011 05:00:46    6.843       0.021 
20.05.2011 05:00:47    6.843       0.017 
20.05.2011 05:00:48    6.838       0.021 
20.05.2011 05:00:49    6.838       0.017 
20.05.2011 05:00:50    6.843       0.021 
20.05.2011 05:00:51    6.843       0.017 
20.05.2011 05:00:52    6.848       0.017 
20.05.2011 05:00:53    6.857       0.017 
...
So far there is very little change in pressure the penguin is on land. But once we get to 07:51 the pressure starts to change, the penguin has entered the water.
...

20.05.2011 07:51:06   13.602       0.525 
20.05.2011 07:51:07   13.607       0.600 
20.05.2011 07:51:08   13.607       0.680 
20.05.2011 07:51:09   13.607       0.756 
20.05.2011 07:51:10   13.612       0.836 
20.05.2011 07:51:11   13.602       0.911 
20.05.2011 07:51:12   13.597       0.987 
20.05.2011 07:51:13   13.592       1.058 
20.05.2011 07:51:14   13.587       1.125 
20.05.2011 07:51:15   13.582       1.159 
20.05.2011 07:51:16   13.587       1.218 
20.05.2011 07:51:17   13.577       1.268 
20.05.2011 07:51:18   13.572       1.314 
20.05.2011 07:51:19   13.577       1.339 
20.05.2011 07:51:20   13.553       1.369 
20.05.2011 07:51:21   13.543       1.390 
20.05.2011 07:51:22   13.528       1.415 
20.05.2011 07:51:23   13.493       1.457 
20.05.2011 07:51:24   13.350       1.520 
.... 

Looking at the GPS data

In deployment no. 7 the logger recorded data from 05:00 20 May to 10:30 21 May 2011. The GPS points we get from the text files can be mapped and connected to generate a track to give an idea of where the penguin went. Here is the track of deployment 7.

Whereas, if we were to just look at the individual GPS fixes the track looks like this:

Looking at the sensor data

Here is what the depth data looks like when opened with dive analysis software:

Here is what the temperature data looks like when opened with MTDive:

You can see that at the time where the penguin is diving corresponds to a time where the temperature data shows very little variation.

From analysis of the sensor data we learn, for example, that this breeding penguin was at sea for 10.5 hours, it made 369 dives the first one at 7:38 and the last one at 15:50. You can investigate all sorts of questions about the penguin's dive behavior from the text files we get from the loggers. The aim of this research is to help us to better understand African Penguin foraging strategy for conservation of this endangered species.

GPS Logger Deployment

 Global Positioning System Temperature Depth (GPS TD) Loggers were deployed on 32 different breeding African penguins at Robben Island penguin colony from May to August in 2011. These devices receive signals from satellites and were set to take a GPS fix every minute in air if they received signals from 3 or more satellites. In May, Postdoc Antje Steinfurth trained Kate Robinson to deploy the GPS TD loggers on the birds. She showed how the penguin should be selected and handled during the process of logger deployment and retrieval.

Here is is an explanation of the process on Robben Island:

Nest Selection
First a suitable nest must be found in the colony. On Robben Island, the amount of vegetation covering nests vary as well as the type of nest.  Sometimes they are simply scapes or depressions in the soil, or they may be under dense rooikrans (an Australian bush)  a natural borrow or an artificial burrow or nest box.

It is best to pick nests that have some form of cover yet are still accessable and easy to see into for logger deployments. The adult penguin at the nest is marked with a biodegradable non-toxic dye so it can be distinguished from its partner.

Monitor adult behaviour

The nest is re-visited to check that the adults are sharing parental care i.e. the adults are switching turns staying on the nest with the chicks while the other goes to the sea to forage for fish. Typically one adult will leave in the morning and return to the nest in the evening to feed the chicks. The parents continue to switch turns until the chicks start getting old enough to be left on their own. The bigger the chicks get the longer they are left on their own. When chicks get get old enough they leave the nest site and form groups of chicks called a creche. At this stage they have their juvenile plummage which looks blue.
When chicks are just a couple days old they need their parents to keep them warm as they can't thermoregulate themselves. So we don't want to disturb adults with really small chicks. Once the chicks are a bit older they can be left on their own for short periods of time yet the adult still sits on them. Adult penguins with chicks that are at least 10 days old but that are still brooding their chicks are the best birds to deploy loggers on.  If the adult penguin's chicks are the right size.in one of the nests that has been monitored, we ready the logger for deployment.

Preparing the logger


The logger must be soldered with a new battery, programmed and then started and run outside. This is done so the GPS can make what is called a "warm start" meaning that it already has information of where satellites should be in the sky at the time when we have set the logger to start.

 It has to run and find satellites for at least 15 minutes. Next, the logger is sealed with waterproof tape and wrapped in bubble wrap. All the the necessary materials are gathered up and we head out into the colony to the nest site.

Logger Deployment

The adult behaviour is observed before commencing the logger deployment. If the penguin shows any signs of stress or unusual behaviour then deployment is not carried out. A bird at another nest will then be selected for the deployment. Deploying a logger also requires good weather. If it rains the bird's feathers will be wet and the logger can't be attached.

If everything looks good to go all materials needed are set out and the waterproof tape is cut into strips ahead of time so that the penguin handling time can be as short as possible.

Gloves must be worn when taking the adult of its nest and care must be taken that the chicks do not run out. At least two people are needed: one to hold the penguin while the the other the deploys the logger. 'Deploying the logger' simply means attaching the logger correctly to the penguins lower back feathers with the strips of waterproof tape. The logger must be placed as far down the penguin's back as possible to minimize drag. It is useful to have a third person to watch the chicks and record the details of the deployment.

First, take the adult out of the nest. The penguin must be held from behind the head at the jaw bone and then also at the feet to keep them still. Gloves are worn by the person handing. You would be surprised how strong and fiesty a penguin can be. Their bills and claws aree sharp so care must be taken during the handling to keep the penguin and handler safe.

 The person holding the penguin must sit on the ground and keep the penguin still and with its back straight for the deployment to be done quickly and efficiently.
The person doing the deployment must feel where the spine is then use a plastic pattern to help lift the correct amount of feathers to be stuck in layers to the waterproof tape sticky side up.

Once layers have been placed all the way down place the logger on top.

The tape is then rolled up around the logger.

Then the pattern is removed.

This is what it looks like at this stage.

Stips of tape are then placed length wise down the logger being carefull to leave a window at the top  exposed so the GPS can receive sattelite signals.

 A few dabs of glue to keep the waterproof tape in place.

 The glue is smoothed out with a piece of tape to make it uniform and so it drys fast.

Some dirt is carefully sprinkled on top of any of the glue that is not dry so no leaves or vegetation will stick to the logger. The deployment of the logger is done.

The adult penguin with its logger 'backpack' is then placed back in its nest with its chicks and the field worker then backs away in a steady calm manner so the penguin remains in its nest with its chicks.

Return the next day cautiously to see if the adults have switched and the logger bird has gone to sea while the partner broods its chicks.