Led Lenser Torches for night birding

To: "Birding-Aus" <>
Subject: Led Lenser Torches for night birding
From: "Robert Inglis" <>
Date: Sun, 20 May 2012 11:18:06 +1000
There has been a comment made in this current thread on LED torches which 
insinuates that powerful light sources are a danger to the wellbeing of the 
vision of birds.

As someone who does a lot of nature photography involving the use of powerful 
torches and camera flash gear I am always interested in claims of possible, 
probable and actual damage to the eyes of creatures, especially birds, from 
such light sources. I regularly hear these claims but so far have never been 
able to find reliable evidence that powerful torches and/or camera flash units 
have adverse effects on the eyes and/or vision of birds. There is certainly 
plenty of scientific evidence that the eyes and eyesight of mammals, reptiles 
and invertebrates are susceptible to damage from exposure to very bright light 
from powerful torches and camera flash units but there seems to be only 
subjective and/or anecdotal evidence that such light sources can possibly 
adversely affect the eyes and vision of birds. 
It should be noted that humans and other mammals such as possums have eyes of 
similar construction so it would be reasonable to expect that, if a very 
powerful light source is damaging to human eyes, then, the same would apply to 
the eyes of other mammals. The same applies to the eyes of reptiles as their 
eyes are of a similar construction to those of mammals. Birds eyes, however are 
somewhat different in construction to those of mammals and reptiles so it 
should be unwise to simply assume the effects created by powerful lights would 
definitely be the same for both classes of eye. The eyes of invertebrates are 
quite different again and there is strong evidence that the eyes of 
invertebrates are even more sensitive to strong light than are the eyes of 
birds, mammals, and reptiles.
It should be noted also, that torches and camera flash units are very different 
sources of light. Torches are used to provide a constant beam of light for a 
sustained period whereas camera flash units are designed to provide a powerful 
source of light for a very short period of time. 

As I have mentioned in previous postings on this topic, I have never seen any 
evidence that the vision of birds has been adversely affected by the powerful 
torches and camera flash units I use in my bird photography. On the contrary, 
my observations have been that the light from powerful torches has had little 
or no effect and likewise for the light from my camera flash units when used on 
birds during day or night photography. It has been my observation on occasion 
that, on activating the flash unit for the first time, some birds are startled 
by something they obviously did not expect. Those birds usually take no notice 
after that first flash and continue to do what they were doing before the flash 
unit fired.
On the other hand, I have certainly noticed that mammals definitely are 
disturbed by having powerful lights trained on their eyes.

I have asked this question before and I ask it again now.
Would someone please point me towards some scientifically proven information 
which proves that the eyes and vision of birds are as susceptible to damage 
from exposure to very strong light such as from powerful torches, LED or other, 
and camera flash equipment. 
I am not interested in subjective comments even if they are from eminent 
scientists; I have read a number of those and they actually prove nothing.

I am happy to receive correspondence on this privately if respondents don’t 
wish to discuss this publically.

Bob Inglis
Sandstone Point

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