Bayliset al. • CAPSAICIN AS A NEST PREDATION DETERRENT 
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Adhesive Capsaicin 
Adhesive Paprika 
Powder Capsaicin 
Powder Paprika 
Untreated 
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Time observed (days) 
PIG. 2. Nest survival over time for the five treatment groups. Adhesive capsaicin-treated eggs had reduced predation 
risk compared to other treatment types (/. = 2.409. n = ISO, P = 0.016). 
to be applied to allow sufficient respiration through 
the unaffected portion of the shell for normal 
embryonic development. Alternatively, use of chili 
powder on the rim of the nest versus the eggshell 
would need to be explored before suggesting broad 
scale application of this approach. 
Applying the chili treatment to real eggs of wild 
hirds would also require locating nests of at-risk, 
native birds, and careful and skilled applicaiion of 
the chili to ensure that eggs were sufficiently 
treated, hut avoiding disturbing the physiological 
function of the egg, altering the behavior of 
parents, or alerting non-mammalian predators to 
'he nest's location. It is likely far more cost- 
effective to apply aerial baits to decrease predator 
numbers, rather than using a large scale placement 
nI artificial nests or a labor-intensive egg-treatment 
method. However, use of capsaicin at known active 
nests of highly endangered species might further 
reduce predation by arboreal mammalian species in 
situations where they are minimally affected hv 
aerial or terrestrial poison baits (Howald et al. 
2007. Oppel et al. 2010). There are also regions and 
sites where use of poison baits is not possible or 
permitted, mainly due to agricultural practices, 
human, wildlife, and pet exposure, or public- 
opposition. These areas tend to lack predator 
control. Capsaicin treatment as used in our trials 
through its application to ical nests as a chemical 
deterrent against predation of Ihc treated nest may 
provide a physiological or a psychological deter¬ 
rent against nest-predation, or both. Thus, capsaicin 
treatment of bird nests and eggs presents potential 
new methodology to be used to decrease mamma¬ 
lian predation effects in areas without poison drops 
and baits, and could be a valuable tool for avian 
conservation management. 
ACKNOWLEDGMENTS 
We thank many colleagues for valuable discussions, 
contributing the quail eggs, and B. J. Gill at the Auckland 
Museum in particular for access to the Land Vertebrates 
Collection. Funding for this project was provided by the 
Human Frontier Science Program (to PC and MEH) and by 
the Faculty of Science at the University of Auckland. PC is an 
ARC Future Fellow. 
