I'll start with the benefits:

Drones can easily overcome line-of-sight issues for radio telemetry, essentially creating an instant radio tower, and flying patterns to receive signals. This can be cross referenced with more advanced positioning technology, such as GPS, ToA, and phase angle, breathing new life into simpler "beeper tag" technology.

Drones, combined with IR and visual spectrum cameras, can utilize machine learning to provide very accurate and real time counts of wildlife. I suspect the accuracy is much higher than traditional counting techniques.

Both above scenarios are ultimately safer for scientists compared to low altitude manned flights. Of wildlife biologist mortality, 66% can be attributed to aviation accidents! This benefit alone cannot be overstated: http://profile.iiaa.org/sites/default/files/images/Obits/Sasse-2000-WSB.pdf

I would imagine that in areas where poaching is a high concern, real time surveillance for law enforcement would be extremely useful -- if not increase the safety of officers on the ground.

However, there are some challenges and weaknesses. There is not much data on how drones disturb wildlife, what altitude is recommended, or perhaps what dB of noise may alter their behavior during the counting process. It would be pretty useless if the drone caused animals to disperse, and the count was underreported.

There are significant challenges from a regulatory standpoint, and i'll try to keep this international. A lot of governments forbid operation over protected wetlands and wildlife areas -- it may be impossible or require special permission. Drone operators might need to be trained and licensed by a regulatory agency. Drones, in some jurisdictions, cannot be flown above a certain altitude or beyond visual line of sight. Some airspace might be also shared with a nearby airport, making flights impossible.

I'll start with the benefits:

Drones can easily overcome line-of-sight issues for radio telemetry, essentially creating an instant radio tower, and flying patterns to receive signals. This can be cross referenced with more advanced positioning technology, such as GPS, ToA, and phase angle, breathing new life into simpler "beeper tag" technology.

Drones, combined with IR and visual spectrum cameras, can utilize machine learning to provide very accurate and real time counts of wildlife. I suspect the accuracy is much higher than traditional counting techniques.

Both above scenarios are ultimately safer for scientists compared to low altitude manned flights. Of wildlife biologist mortality, 66% can be attributed to aviation accidents! This benefit alone cannot be overstated: http://profile.iiaa.org/sites/default/files/images/Obits/Sasse-2000-WSB.pdf

I would imagine that in areas where poaching is a high concern, real time surveillance for law enforcement would be extremely useful -- if not increase the safety of officers on the ground.

However, there are some challenges and weaknesses. There is not much data on how drones disturb wildlife, what altitude is recommended, or perhaps what dB of noise may alter their behavior during the counting process. It would be pretty useless if the drone caused animals to disperse, and the count was underreported.

There are significant challenges from a regulatory standpoint, and i'll try to keep this international. A lot of governments forbid operation over protected wetlands and wildlife areas -- it may be impossible or require special permission. Drone operators might need to be trained and licensed by a regulatory agency. Drones, in some jurisdictions, cannot be flown above a certain altitude or beyond visual line of sight. Some airspace might be also shared with a nearby airport, making flights impossible.

In my experience, multicopter-type drones are met with great suspicion by most large mammals that I have observed, even when flown at normal maximum height above ground level (400 ft, usually), leading to escape responses. They are very noisy! But I suppose fixed-wing, faster flying vehicles might be less likely to disturb animals as they are generally quieter, but I have no data to support this suggestion.

However, there is no doubt that being able to "look" over the trees can be a huge benefit for localizing animals. If used for this purpose (i.e. reconnaissance from a distance), it is worth investing in high resolution goggles as the animals, which small specks, are very difficult to observe using a small screen, or even a larger one (e.g. iPad).

As a pilot, I was very interested in the article mentioned above! However, I have always followed recommended altitudes, usually 2000 ft, but always above 1000 ft AGL, to avoid issues with stalls, power lines, and radio towers!

So depending on the type of drone you use, they can be susceptible to windy conditions. Battery life in multirotors is quite short so have a few spare. An advantage of drones is that they can fly below high clouds - an advantage over satellite imagery. We have successfully used them to count cliff nesting vultures and counting other dangerous animals in difficult to get places such as hippos and crocodiles. We have also noticed different disturbance effects on animals - these differ from species to species and life stage of the animals. So for example a giraffe cow with a young calf was much more nervous of the drone than non-breeding animals were. We are also aware of bird of prey interactions. Personally I think the real value of using drone technology will come in association software development such as object identification and counting.

Yes, always have spare batteries, and a car charger handy. Also, it is useful to have a battery warmer if working in cold climates as the lithium polymer batteries have very low power output at cold temperatures. I have used a cooler bag with chemical hand warmers in a pinch for this purpose.

A blimp (Zeppelin) drone might be quieter. The following study an example of such:

Murden SB, Risenhoover KL. 2000. A blimp system to obtain high-resolution, low-altitude aerial photography and videography. Wildl. Soc. Bull. 28(4): 958-962

Cited in: https://www.nrcresearchpress.com/doi/full/10.1139/[email protected]#.WhQW8UqWa00

A blimp would be a great idea. I wonder if there are any small ones available that have the sorts of navigation capabilities seen in the more readily available commercial drones? This would help with both endurance and noise issues, although wind would become and even greater challenge.

Here, in Cape May, NJ USA, we have a unique authorization from the FAA to operate drones at higher than 400 ft and beyond line of sight. (There are also about 6 test sites across the country here). When I say drones, I don't mean your battery powered DJI, but large fixed wing fuel based drones that have endurances of 12-24 hours. While companies like American Aerospace and NASC primarily fly missions using FLIR, 3D imaging and high resolution cameras at several thousand feet, there is an increased need for additional scientific payloads. Since they are already flying missions performing aerial photography and getting the data back in realtime, I would imagine it is only a short time before this data is captured primarily for wildlife counts of shorebirds and other animals that can be easily sighted from the air. Resolution is measured in mm's, as opposed to traditional higher altitude aerial photography or satellite based imaging.

I have been investigating both fixed-wing and rotary-wing unmanned aircraft systems for natural resource-based applications for nearly a decade. If you send me specific questions, I'd be glad to assist you.