Hi Kate, It all depends on the specie and data set accuracy you are trying to collect. If you are purely documenting frequency of visits, this is straight forward. However, if you are recording numbers then further analysis of photos may be needed. Some animals like foxes have distinctive marks or shapes, whilst smaller mammals can be a lot harder. If this is impossible, then a time limit should be defined across all camera traps. From all the papers I have read and projects we have worked with, there doesn’t seem to be clear standard. Hope this helps. Mike - handykam

Hi Kate, this may be a bit late for your analysis but I will put here for future reference. The case you mention would be to detemine independent events, not necesarily different individuals. Unless there is conspicuous colour, pattern, size, sex or other scars/markings then you shouldn't label them as different individuals. I haven't found much analysis or discussion on this point so it seems prior experience or a "best-guess" is used to determine the time between independent events. Within the R package "camtrapR" vignette it is mentioned (https://cran.r-project.org/web/packages/camtrapR/vignettes/DataExploration.html) "The criterion for temporal independence between records ... will affect the results of the activity plots" and you may have other data to correlate activity with abundance or density.

If you are using and occupancy analysis this may be trivial as you will likely be lumping multiple nights of survey into a single detection period for each camera anyway (we have used six 10-day detection periods for cats in central Aus). 

SECR methods may also be more useful for calculating density. Timing of events BETWEEN cameras can be used to show that photos are of different indivduals as they cannont exist in two places simultaneously or travel at fast enough rate to be captured in that time frame (clocks must be synchronised). 

I hope you have had as good a season in Bon Bon as we have in Alice Springs. Cheers, Al

The facts are simple. If you violate the assumption of independence of sampling events you will bias the result. In the event of multiple observations by overestimating occupancy due to counting the same animal twice. There is therefore no answer to your problem. People try to overcome it by chosing a particular random number to try and standardise the method across sampling sessions. Let us say we decide to use one hour between new samples in all our sampling sessions. If abundance changes between sessions our ability to detect an animal may change and our result may therefore be biased up or down depending on the trend. So we allow detectability to vary between samples to try and reduce this bias. This is done through assessing the results of the replicate samples i.e. n days.
However, the session time determines how many counts are reduced to presence only and as session time increases the variance of the occupancy estimate may grow. But we don't know if this increasing variance/ loss of accuracy is based on a real loss of information or not because we don't know if we are correctly throwing away information portraying the same individual or information on the presence of multiple individuals. Therefore selection of session time may effect our ability to detect a change in occupancy even with accounting for varying detection. i.e. detection may be equal if our session time is too short. In other words if in both one hour AND two hours we detect multiple animals on the same number of plots, convert this to the binomial (presence/absence), then detectability will be equal for both sessions. But if in one hour we detect half the number of animals as in two hours what does this say about occupancy?
Spatially explict (SE) models will also not help because as far as I know they are based on allowing multiple detections across plots, not within plots. Or cameras in this case.
Having said this there is apparently some hope in marking a portion of individuals to increase the accuracy of SECR or SE unmarked in this case. So my only advice would be to run an experiment with marking some foxes and use a SE model with predominantly unmarked indiviudals.
On a more jovial note you could simply mine the data by assessing the power to detect a change between pre/post baiting using a variety of different session times. The reality of such a result is highly dubious but it might inspire more thought on the behaviour of this particular situation. Failing all this youy could run away and join the circus.

I am finding ArcGIS Collector very usefull. I can say, as an dedicated R coder, some things are worth paying money for and Collector is one of the. I have used it to implement several monitoring and data collection projects. I particularly like the assurance that data will not be lost on the device and the ability to cache base maps. 

Dear BPdorsey, Collector will support custom basemaps ? It wasn't an option a few months ago.

CCI International GIS Day recap

GIS Day at CCI was a great success! We kept it short to try and maximise engagement and so that everyone could meet each other. Attendees have been sent a follow-up email, but if you've not received this or you want to know more then please message me for details.

It would be a great mini-legacy and a testament to the event if attendees could post a brief introduction / recap on this thread; just stating your occupation and interests, or anything that you took away from the event. Thanks to the organising committee @jonathanknox.ffi (FFI), @Tomswinfield (RSPB) and Andy Arnell (UNEP-WCMC). And thanks for the photos, @StephODonnell !

I'm a software developer with the British Trust for Ornithology (BTO), working on online map-based applications for bird surveys (e.g. BirdTrack). My main focus is the databases (Oracle & Postgres, including spatial features) and preparing the GIS data using ArcGIS or QGIS. Our online applications are key to receiving survey data from a large number of volunteers and displaying the survey results back to the volunteers.

I also act as central contact point within the BTO for queries about GIS.

Hi Heidi,

You might also consider becoming involved in the eMammal project (emammal.si.edu) that the Smithsonian has recently developed. It has tools for both uploading and coding camera trap images, with the bonus that they are ultimately archived and made available by the Smithsonian for future researchers. My opinion is that moving toward open-access data will make all of our efforts more valuable into the future. I'm using eMammal, but not one of the developers or associated with the Smithsonian.

Cheers,

Robert

Hi Megan, 

It sounds very interesting the app you are developing. I am working for a smaller nature conservation Fund and am trying a partnership with a platform that is also in development and aimed at connecting people and organizations, facilitate update and knowledge sharing and increasing the visibility and donor pool of the organisations. As I said it's still in development but you can take a look if you like www.pifworld.com/eng. I am however also very curious to get to know other (potential) tools that work similar.

It would be great to chat one time to get better acquainted, maybe you can send me your contact details by PM if you'd like to follow up?

Best, Anne Alexandre