FAQ's

• Tags

• Can I change the Tag Antenna Length?

  You can always cut down the antenna when in the field. A sharp and strong pair of wire cutters are best. The end should be neat so that it does not fray. However, by cutting down the antenna, you will reduce the range more than if the antenna was made with and tuned to the shorter antenna originally. For the first season you may wish to try the longer antennas, because they will give longer ranges. If there seems to be a problem the antennas should be cut down in the field. But on refurbishment, or buying new tags, please advise us how long you would like the antennas to be.

• Can you re-battery / refurbish / recycle used tags?

  We can rebuild used radio-tags. We tend to use the term refurbish because we do not only change the cell of the tag, but also fit new antennas, collars etc. and rigorously re-test the tag for reliability. In this way you effectively get a brand new tag. This costs just 80% of the price of new tags. Please note however that we cannot change the frequency or pulse parameters of tags during this process.

• Coded Tags or Beeper Tags?

  Beeper tags are easier to use for manual tracking than coded tags. However, there are certain situations where coded tags are better than the more traditional "beeper" tags, predominantly when there are large numbers of birds to listen through and it is important not to miss an event.

  To explain the advantages of coded tags, here is an example. Consider if you have 40 birds that are returning to a colony to feed their chicks, and the visit time is 2 minutes. With beeper tags all on different frequencies, the logger would listen to each one for at least 5 seconds each (5 x 40 = 200 seconds), and loose about 5 seconds (switching between birds) so 205 = 3.4 minutes. Therefore it takes more than 2 minutes between logging the same bird and in that time the bird could have come in, fed its young and left without any possibility of the event being recorded.

  Lotek's coded nanotags are all on the same frequency, therefore the DataSika logger (or more sophisticated SRX Loggers) can be listening for all tags at the same time, and would not have missed that event. If two tags are around at the same time, their pulse intervals are different to reduce congestion. If you are considering large numbers of birds there is another option to minimize congestion, so please ask.

  Lotek's coded nanotags get over this, and the DataSika logger (or more sophisticated SRX Loggers) can decode the signals. It is worth noting that tracking to find the location of the animal is less easy with coded tags, so really this is best designed for presence/absence studies.

• Do you make Micro-controlled tags?

  We have the ability to build micro-controlled tags, but generally we find that we can get tags to last longer without the micro-controller, because of the high current it draws.

• How long can I store my tags for?

  The capacity of a silver (Ag) cell starts to decline as soon as it is soldered to. Therefore, any small tag should be used as quickly as possible, to ensure that you still have the estimated battery life. If the tags are kept for longer than 6 months, even if you have not activated the tag at all, then it is advisable to replace the battery. Unfortunately it is not possible to check the capacity remaining in the cell without using it. Cells are designed to maintain the voltage until just before they finish, so measuring voltage does not measure capacity.

  If you can not get the tags refurbished, then it is best to use the tags as quickly as possible, but be aware that the tags may not last as long as predicted.

  Larger lithium celled tags (e.g. with 10-28, 1/2AA etc.) can usually be stored for more than a year – as long as they are properly turned off.

• How to start Geolocators?

  For LAT series tags, developed by Lotek, download LAT TagTalk from Lotek downloads.

  Once installed there is a manual in the Documentation Directory.

  For M-Series tags, developed by British Antarctic Survey (BAS), download the short manual from the Datasheets page: see Geolocator M-Series Short Manual

  Please note that both tag types need different interface leads with the computer.

  For a great example of how coded tags have been used, see this clip of Greg Mitchel on youTube.

• Solar Tags, do you supply them?

  We do not supply solar tags, because they generally do not last any longer than ordinary tags. Solar-powered tags are attractive because they seem to offer the prospect of infinite battery life. Because of this they are easy to sell ! However, they have a number of intrinsic limitations, and at Biotrack we have decided not to supply them. The first limitation is the re-chargeable cell, which is charged by the solar panels. This has a finite life, even if the solar panels do not. Furthermore, rechargeable cells have inherently low energy density, and thus are bulkier than primary cells. The additional circuitry, and the inclusion of a solar panel, makes solar tags less reliable (for example, if the bird dies and is lying on its back, or is hidden in vegetation the solar panels will not work). The solar panel has to be exposed (i.e. not covered by feathers) which potentially increases the drag factor of the tag. In contrast, tags with primary cells are at least partly preened into the plumage.

• Tag signal range - what is it?

  One of the most important performance parameters of a radio tag is its signal range. Unfortunately this is also the most difficult parameter to accurately predict. The variability of range in the field is due largely to the effects of topography, habitat, tag and receiver height, and receiving system performance. If a tag fitted to a large soaring bird living in open country is compared to a tag with the same power output fitted to a ground-dwelling mammal in rainforest, the range of the bird tag could be up to 50 times greater! Of course, these are two extremes of habitat and height. Most projects fall somewhere in between, but still the effects of habitat and animal behaviour can be quite dramatic.

  Some of the terminology used to describe range is also rather misleading. For example, the phrase 'line-of-sight' is often used in range descriptions. This is not, as it implies, the range you would get if you could see the tag (that is, no obstacles between you and the tag). Rather, it is the 'free-space' range, achieved only if the tag and receiving system were at high altitude. The nearest radio tracking gets to true line-of-sight conditions is when a tagged bird in flight is tracked from an aircraft or a very high hill. We continue to quote line-of-sight ranges, mainly because it is the convention to do so. However, we suggest you consider them only if you plan to track high-flying birds from high points or aircraft.

  A more meaningful range figure is 'ground-to-ground'. It is the signal range to be expected over open or lightly-wooded flat terrain, with the tag on the ground. The signal strength reaching the antenna is assumed to be -145 dBm (about the weakest signal you will hear in the field) and the receiving equipment is assumed to comprise a good-quality tracking receiver and 3-element Yagi antenna. The range is much lower than that achievable to an animal above ground (in flight or in a tree, for instance), but higher than if the animal was below ground or hidden in dense vegetation. In most cases the range to a tagged animal on the ground will still be better than our quoted 'ground-to-ground' range because the tag itself will be at least a few cms above ground when it is attached to an animal.

  For species that spend some of their time in flight or in trees, the signal ranges given under 'above ground' conditions are meaningful. These are based on tags that are at least 3-4 metres above ground. These ranges also apply if the receiving system can be raised, such as by tracking from higher ground, or having an antenna on a mast.

  There are a number of ways to improve range, the most obvious of which is to increase the power output of the radio tag. Unfortunately this has implications for battery life, and it is often impossible to have high power transmitters that also have sufficient battery life. In such cases, it is possible to improve signal range by improving the performance of the receiving system. Usually the simplest way to improve receiving system performance is to raise the height of the antenna. Even holding it above your head will help ! If that is not enough, it is possible to mount antennas on vehicle mounted masts, or - for better portability and lower cost - to mount a special light weight antenna on to a telescopic fishing rod (e.g. 'roach pole').

  During fieldwork it is often necessary to track from high points (e.g. hills and trees), especially if a tag is missing. If all else fails, radio tags on dispersed animals can be located from aircraft. This is a routine technique in many projects, and is not particularly expensive in comparison to a ground search over a very large area. Signal range from the air is much better than on the ground (perhaps 10 x or more) and the speed at which an aircraft covers an area is vastly better than the speed of doing it in a vehicle on the ground. The biggest problem with aerial tracking is that you need special clamps to safely attach Yagi antennas to aircraft wing struts. These are available from some of the larger US telemetry companies. Of course, you also need a pilot who is prepared to allow you to strap the antennas to his aircraft! For a detailed description of aerial tracking techiques, see Kenward 1987.

  Reference
  Kenward, R. E. 2001. A Manual for Wildlife Radio Tagging. Academic Press. London. [An excellent introduction to all aspects of radio-tagging and radio-tracking, including a section on DIY tag construction.]

• What are 'transmitters'?

  Radio transmitters are small sealed units that contain the electronic circuitry needed to produce radio signals. To be built into a radio tag, they must be fitted with a battery, antenna and mounting system (e.g. harness tubes for a backpack), and then encapsulated in resin ('potted'). For more information, Radio Tags page.

• What are Coded Tags?

  Coded tags are VHF tags that send codes rather than simple beeps, allowing for more than 200 tags to share the same frequency.

  To explain the advantages of coded tags, here is an example. Consider if you have 40 birds that are returning to a colony to feed their chicks, and the visit time is 2 minutes. With beeper tags all on different frequencies, the logger would listen to each one for at least 5 seconds each (5 x 40 = 200 seconds), and loose about 5 seconds (switching between birds) so 205 = 3.4 minutes. Therefore it takes more than 2 minutes between logging the same bird and in that time the bird could have come in, fed its young and left without any possibility of the event being recorded.

  Lotek's coded nanotags are all on the same frequency, therefore the DataSika logger (or more sophisticated SRX Loggers) can be listening for all tags at the same time, and would not have missed that event. If two tags are around at the same time, their pulse intervals are different to reduce congestion. If you are considering large numbers of birds there is another option to minimize congestion, so please ask.

  Lotek's coded nanotags get over this, and the DataSika logger (or more sophisticated SRX Loggers) can decode the signals. It is worth noting that tracking to find the location of the animal is less easy with coded tags, so really this is best designed for presence/absence studies.

• What battery life with I get from my tags

  Larger batteries have larger capacities and will therefore last longer. However, it is also dependent on pulse rate (faster pulses use up the capacity faster) and pulse length (longer pulses give better range but reduce the capacity more for each pulse). To investigate this use the tag chooser to select a tag, then in the Tag Life link alter pulse rates and pulse lengths.

  For tags with two cells, they can be run in parallel (normal) or in series to increase the range. However running in series, at twice the voltage, reduces the battery life substantially.

• What does 'Potting' mean?

  Potting is the protective layer around the transmitter and cell. Tags that might get chewed, or are likely to be submerged need heavy potting, whereas small birds need tags to be potted lightly, because they are unlikely to damage the tag and it is important to keep the weight down.

• Will my antenna work with my tags and receiver?

  The antennas we supply work best over a 4 MHz band. Therefore an antenna centred on 150 MHz will work well between 148.000 - 152.000 MHz. Outside of that range the user will loose gain and directionality. The major concern about working with the receiver is the connector. Our antennas (and receivers) have the standard BNC connectors. The frequency of the tags must be within the range of both the receiver and the antenna.

• What is connectivity?

  Migratory connectivity is the degree to which breeding and non-breeding populations of birds are linked to one another in both space and time, which is fundamental to other processes such as population dynamics, dispersal and colonisation.

• Attachment

• Break-away collars, do you supply them?

  Many researchers wish to study survival and dispersal in juveniles that are still growing and a breakaway collar appears to be the solution. Unfortunately we do not supply such tags because of the huge risks involved. We are too remote to be able to judge the collars effectively, or deal with any problems should they arrive. Providing equipment commercially we have responsibilities ensuring that the tag will work properly. Judging when a weak link will break under different conditions is extremely difficult. If the link breaks too early researchers will be unhappy, because a lot of battery life is wasted, but they will be even more unhappy if the link does not break and the collar strangles the animal.

• How do I attach tags to birds?

  Download the datasheet at Mounting Tags on Birds

• What's a physiocompatible coating?

  Physiocompatible means not reacting with the tissues surrounding the tag. Implants are coated in a non-corrosive silicone rubber; Dow Corning 3140 RTV coating. This is to prevent infection and the body juices corroding the tag.

• Frequency

• Frequency band - what is it?

  RECEIVER FREQUENCY BAND

  When ordering tags we need to know the frequency band of your receiver. If you do not have a receiver then you will have to decide what frequency band to use before you order it.

  Different receivers have different band coverage, though most are available on all the frequencies commonly used for radio-tracking. Our new Sika receiver overcomes this problem by covering the range 138.000 MHz - 173.999 MHz. However, most receivers only cover 1 MHz, e.g. 142.000 - 142.999 MHz or 150.500 - 151.500 MHz.

  The band coverage has implications for the number of tags that can be used on a single study site. If all the tags are to be on distinct frequencies, they should be spaced by about 10 kHz. This means that a receiver covering 150 kHz can be used to track up to 15 tags. A receiver covering 1 MHz, as most frequency synthesis receivers do nowadays, has enough band for up to 100 tags.

  When considering what frequency band a new receiver should cover, the following considerations apply:

  1) If possible, you should use the frequency allocated to radio-tracking (or low power radio devices) in the country or region where the equipment will be used. To find out more information about radio-frequency allocations in your part of the world, please check the Low Power Radio Association’s website for relevant wesbites with contact information.

  2) If no official frequency is allocated, a wider choice is available. However, the frequency band chosen must be one that is not in use for other purposes. Most other users of the radio spectrum operate very high power transmitters that will completely swamp the signals from radio tags. Your tags are very unlikely to upset other users, but the signals from powerful transmitters can have a profound impact on your tracking and your ears ! It is particularly important to avoid frequencies used for communications and public broadcasting.

  When you have a free choice of frequency band, apart from the constraints mentioned above, you should choose one of the bands commonly used around the world for radio-tracking (these are 142, 148, 149, 150, 151, 165, 173, 216 or 230 MHz). If you are preparing a foreign expedition, you should give preference to the frequency allocated to tracking in your native country, so that when the expedition is over, the receiving equipment can be used at home without modification.

  3) Some properties of radio propagation also affect the choice of frequency. High frequencies are attenuated by vegetation to a greater degree than lower ones. So, for example, lower frequencies are preferred for tracking in rainforest. On the other hand, at low frequencies, tracking antennas are larger and rather unwieldy. If you are tracking in densely vegetated habitats, you should consider using an antenna with flexible elements.

• I can hear my tag in two places on my receiver: Sideband Frequencies.

  All tracking receivers develop two frequencies from the single frequency of the transmitter. These are called the upper and lower sidebands. The IF (intermediate frequency) filter inside the receiver should all but remove one of them. If the filter was not present you would hear each tag at equal strength at two places on the receiver band. Unfortunately, no IF filter can completely remove the second sideband, so you can still hear the tag at two tuning positions, but one of these should be much louder than the other. Usually the difference is so marked that you will never notice the 'wrong' sideband. If the filter is not as good as it should be, you may accidentally tune in to the wrong sideband. At close range - e.g. as you are putting the tag on the animal - the signal may sound fine. In the field, however, tracking the wrong sideband will give much worse range.

  Apart from the difference in signal strength between the sidebands, you can also tell the difference by the way the tone of the bleep changes as you tune through the band. The two sidebands are mirror images of each other. If you start tuning from below the lower sideband, as you tune slowly into it you will hear the pitch of the bleep decreasing. As you continue to tune through, the bleep becomes a thud and may disappear completely (the 'null' point). Keep tuning up through the band and you will start to hear the upper sideband. For this sideband the pitch will start low and increase; the opposite (mirrored) way to the lower sideband.

  Once you know which is the stronger sideband on your receiver, you can check the other tags to see if you are tuned to the correct sidebands on these. You can tell by the way the pitch of the bleep changes as you tune up the band.

• Will my tags work with any receiver?

  If your receiver is designed for radiotracking AND is designed to cover the same frequency band as we make the tags on then Yes. Ensuring that we are building the tags on the right frequency band for your receiver is crucial, and it can take a long time to order crystals, so it is important to tell us your frequency band as soon as possible.

• Yagi Antenna frequency bands?

  The antennas we supply work best over a 4 MHz band. Therefore an antenna centred on 150 MHz, will work well between 148.000 - 152.000 MHz. Outside of that range the user will loose gain and directionality.

• Receivers

• Can I use an ordinary scanning receiver?

  Scanning receivers are much cheaper than those designed for radio-tracking, because their market is much larger. Unfortunately, even though you may be able to hear your tags on such a receiver they are no good for radio-tracking. The vast majority do not have gain controls and most are frequency modulated, to try and keep the signal the same volume, both of which make them useless for direction finding. Moreover there are hidden complications to do with how the signals are mixed in the front end that may mean you will not hear certain tags at any distance, or when another signal interferes. This is more difficult to check, but will lead to problems.

• References

• References to radio-tracking studies

  This website now contains searchable abstracts, linked to from our research page. This database will grow, and if you have any suitable publications you would like others to investigate, please send them to sean@biotrack.co.uk. Alternatively Robert Kenward's "A Manual for Wildlife Radio Tagging" is a useful book with many references, see the Tracking Kit page.

• Sales

• Can I pay by credit card?

  We can accept payment by credit cards. There is a 3% surcharge to cover the costs and the following cards can be accepted: Visa Credit, MasterCard, Visa Debit, Visa Electron, Maestro, JCB.

• Delivery / lead time

  Please contact us as soon as possible to ensure delivery in time. By our standard delivery, tags are sent out eight weeks after receiving an order. During March to July our schedule can get full even further in advance. However, we can often build tags at much shorter notice, so please let us know even if you think the time is too short. It is very helpful for us to plan ahead so, even if you are unsure of funding, we would like you to let us know what you might need. We can then make a provisional order which can be altered or cancelled easily nearer the time. PLEASE NOTE: We must know the frequencies you are working with as soon as possible if we are to deliver tags on time.

• Discounts, are they possible?

  We give a bulk discount of 5% off orders for more than 50 tags. Because all our tags are highly customised and labour intensive, there is no economy of scale. However, this gives you what you need for your tracking requirements.

• How will my equipment be delivered?

  Often we can use the ordinary post; it works well and is economic. However there are occasions when couriers must be used due to the location, insurance or time constraints. We prefer to use couriers of our own choice as we have experience with them in particular regions, and have better deals on those we use most. However, in places where we deliver infrequently, customers are more knowledgeable about which couriers work best. In that case, please give us your preferred courier and we will see what can be done.

• Payment

  Proforma invoices (quotes) are issued on request. On receipt of an Official Order we issue an Order Confirmation giving costs and delivery details. At date of despatch we issue a Final Invoice, which must then be paid within 30 days. We reserve the right to require payment with order. Payment should be made in Pounds Sterling (or US Dollars or Euros by special request) by a cheque drawn on a London bank, by a direct bank transfer or by a giro. We can also accept payment by credit cards. There is a 3% surcharge to cover the costs and the following cards can be accepted: Visa Credit, MasterCard, Visa Debit, Visa Electron, Maestro, JCB.

• Provisional Order Scheduling

  Biologists are often unsure of funding for a project until just before fieldwork is due to start, and it may then be impossible to get equipment built and delivered in time. We can help by scheduling time for tags to be built, based on a provisional order made before funding is secured. We will not start building tags unless an order is confirmed, and we need to know at least 4 weeks before tags are due to be despatched. Please ask for further details if you would like to use this service.

  PLEASE NOTE: We must know the frequencies you are working with as soon as possible if we are to deliver tags on time.

• Terms of Business

  BIOTRACK LTD - TERMS OF BUSINESS

  Basis of Contract

  1. Biotrack Limited is an English registered company number 2895873 ("the Company") whose registered office at 52 Furzebrook Rd., Wareham, Dorset, BH20 5AX and which designs radio tagging devices and ancillary goods and services ("the Products").

  2. These terms apply to all sales of the Products to the exclusion of all other conditions save insofar as they have been varied by the Company in writing.

  Timing of Delivery

  3. The Company will endeavour to meet any agreed time for the delivery of Products to its customers but it is not responsible for any delays caused by circumstances beyond its reasonable control.

  New Technology

  4. Production of tagging devices involves work at the margins of technology in this field and the customer undertakes that it has provided all information reasonably needed for the Company to evaluate its requirements and that all information so provided is full and accurate.

  Prices and Terms

  5. All invoices are due for payment within 30 days from the date of invoice. All other payment terms are on the quotation/pro forma invoice.
  6. Any prices quoted do not include importation duties (if any) that apply. Such duties are for the Customer's account.

  Title/Delivery

  7. Title to the Products will pass upon proper despatch to the customer and delivery shall take place when the Products have been received by the customer and they have had a reasonable amount of time to inspect them. Customers are required to give notification to the Company within 14 days of delivery of the Products if the Products appear to be damaged or they have any reason to believe that the Products will not function properly or satisfy the requirements of the Contract.

  Warranty

  8. (a) Provided the Products are stored, transported, fitted and activated in accordance with the instructions given by the Company, then in the event of a defect in the Products during the operating life specified and which can be shown to our reasonable satisfaction to be due to defective materials or workmanship then we will at our option replace or repair the Products that we find to be defective or refund to the customer the cost of the Product in lieu of such replacement or repair.
  (b) This warranty shall be invalidated unless the customer shall inform the Company within the specified period and within 14 days of discovery of the defect.
  (c) If the Company so requests and it is practical, then the customer will return the defective Products to it.
  (d) The Company offers no warranty in respect of components forming part of the Products that were not manufactured by it but will use all reasonable endeavours to assist the customer wishing to make a claim against the manufacturer of a faulty component.

  Limitation of Liability

  9. (a) The Company's liability in negligence for death or personal injury is unlimited.
  (b) The Company shall have no liability to a customer for any indirect or consequential loss arising out of breach of Contract (including liability for any damages arising out of the inability of the customer to proceed with any planned experimentation) in respect of which the customer should insure.
  (c) Save as specified above the Company's liability shall be limited to the higher of the amount recoverable under its insurances or the value of the contract.

  International

  10. Whilst the Company endeavours to comply with any controls (regulatory or otherwise) which may affect the use of the Products outside of the United Kingdom, it is the responsibility of the customer to draw any special requirements to the attention of the Company before work on the production of the Products commences.

  Legal

  11. The Contract shall be construed in accordance with English law and subject to the non-exclusive jurisdiction of the English Courts and shall be deemed to be made within the area of jurisdiction of the Poole County Court.

  Waste Electrical and Electronic Equipment (WEEE) Regulations

  12. The end-user accepts the obligation for appropriate disposal of used Products under WEEE regulations. Biotrack will refurbish used products where practical.