Hi Andrew. 
I think it would be good to also include your size, cost, battery, accuracy, and ruggedization requirements. Depending on what these are, it could be easy or difficult to find what you’re looking for. 
Regards. 
Akiba

Hi Andrew and others,

There is a way to make a cheap logger, and I would attempt it except I'm not in a good position at the moment to do so.  So I'm putting this out there in the hope that someone else in the tech sector @Freaklabs maybe would be able to take it up and fill in a very obvious gaping hole in the market.

The solution I am proposing is based on the STM32F411 Black Pill stamp (512k flash, RTC) and a GY-BME280-3.3  (temperature/barometer/RH) Bosch sensor board and 2  or 3 AA alkaline cells.  Total BOM cost would be around USD10.  I do not recommend the SHT11 as it does not age well.

A custom PCB is not required.  Instead the Bosch module is soldered directly onto the stamp, such that the I2C pins of the MCU and BME280 match up.  Since the BME280 is a very low power chip, power and ground can be fulfilled with GPIOs.

Data are saved directly into the MCU's flash, and can be retrieved by USB (the MCU being configured as a FAT12 mass storage device).  Similarly, the logger can be configured by drag-and-dropping a config file onto the MCU via USB.  The code can occupy the lower 112k of flash, leaving the massive upper 3 flash sectors (384k) for the logged data.

There are a couple of fine points.  On some (most?) black pill boards, the RTC's crystal oscillator capacitors are of the wrong value (around 10pF) which makes the RTC rather inaccurate.  This problem is easy to solve by replacing the 0402 caps with ones of the proper value (15 or 18pF).  Alternatively, leaded capacitors can be added in parallel to make up the capacitance.  Any remaining RTC drift can be addressed by programming the appropriate RTC registers.  Any board work done in this regard must be followed with a very thorough cleaning, or the RTC oscillator may refuse to start up due to residual flux.

Finally, the power LED may need to be disabled for true low power sleep.

A housing can be 3d-printed to suit.

Thanks

Hi Andrew,

If near real-time data is of interest, another option is to move away from standalone loggers and use a low-power wireless sensor approach. The BME280 Harold mentioned would be fairly straightforward to integrate where I²C/SPI interfaces are supported.

The main advantage is visibility. Instead of discovering issues perhaps months later, you would see both data and device health in real time. That can be useful if a unit fails or gets damaged, which sounds like risk in these nesting boxes. It also allows you to vary sampling rates if you want higher resolution during periods of interest.

Deployment practicality will depend on site conditions, but these types of systems are already being used in remote ecological settings, including arboreal installations where infrastructure is mounted in/around canopy environments.

Happy to share more detail if it is of interest.

Cheers,

Simon

Hi Andrew,

We used some bluemaestro discs and they seemed to be very good, until they stopped working. No reason, they would stop working, they were indoors. 

So wouldn't recommend them, specially for a challenging environment (nests).

Good luck.