Over the past few years I have become more and more involved in amphibian surveys here in the UK. Firstly I started out doing surveys in the day time but then after starting university these surveys switched to night. Are there any articles that compare daytime and nighttime surveys to show that night is best when surveying for amphibians?
Hey Steven,
What kind of surveys were you doing in the day time and what kind of surveys were you doing at night?
For example, if I'm sampling the larvae of pond breeding species or aquatic salamanders, I'll sample in the day time, but if I'm out to round up breeding adults or do vocalization surveys then I'll go at night.
There are plenty of exceptions to this, but it depends on the species, life stage, habitat, etc.
Cheers,
Paul
Hey Paul, my methods sound pretty much similar to yours. Day time counts were for spawn or larvae (with the occasional adult seen, but the survey wasn't particularly aimed at them). Then I got interested in surveying for the adults so we switched to a night time survey. At night, I use a torch to detect adult newts or anurans in and around ponds.
Steven,
I have used both daytime surveys and nighttime surveys and trapping to detect the presence of frogs and toads. The nighttime surveys always are more productive. Frogs and toads call more readily after dark, and adults and larvae are generally more active at night. Call surveys always detect more species than daytime searches, and overnight trapping is far more productive that simple day surveys. I use simple minnow traps "baited" with glow sticks to capture tadpoles during the night. Compared to "unabated" traps that capture actively swimming tadpoles, "baited" traps regularly capture far more individuals. Drift fences and pitfall traps can be used similarly to detect amphibians moving during the night to breeding areas. There are many references for these methods.
It depends on the species you're after, and in some cases the levels of disturbance but generally you get much higher counts for newts, especially Triturus cristatus, at night. NCC (1989) guidelines predict double the count at night but in practice it can be much higher. Torching (flashlighting) causes less disturbance and damage than netting too, though can disturb non-target spp such as otter and roosting birds. Moon phase can also affect counts (Deeming, 2008 Herp J 18, 171-174): Lissotriton vulgaris counts peak around the new moon and T. cristatus in the days coming up to the new moon.
Again, depends on species/group you're surveying. As ecologists, you want to keep your disturbance to a minimum - hence the beauty of using vocalisations as a means of surveying frogs. You also want to survey at an appropriate time regarding the natural history of the species you're investigating. As many frog species are active at dusk/night, then surveying at this time makes a lot of sense. Working at night also acts to focus your senses in terms of sound (most diurnal species remain relatively inactive) and sight (basically, if you're searching via a torch/flashlight, your eyes are focused within the limits of the beam). In the past, I've simply wandered along rivers/waterways at night, recording frog species (and ROUGH numbers) based solely on calls. It is most important to standardise your approach, particularly in terms of what others have done (look again at that paper that Colin suggested above) and record as much environmental data as you can.
Hey Steven,
As has been said by colleagues depends on species you are wanting to sample, the question of its study and how much time you have to sampling. If you are studying the species richness of the ideal is to work during the day and night. Some species are more active during the day and many are active at night. Night activities, probably is related to physiological factors (decreased desiccation), behavioral (defense against predation), among others. The use of traps like pitfalls is very important to complement sampling. If you can inspect the traps at least twice a day, early in the morning and and the end of the day, you can get information about the species activity period.
Hey everyone, thanks for all of your input. It has been very helpful.
If you are interested in the total amphibian population in any given area, you must survey both during the day and at night. While it is true that most amphibians are actively vocalizing at night, there are many, many exceptions to this rule. I am thinking of the dendrobatids in the New World tropics, as one example.
I think Amphibians are more abundant in the night and one tend to be able to capture more than day time this is particularly very true in the tropics
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