Action

Relocate nests/eggs for artificial incubation: Snakes

How is the evidence assessed?
  • Effectiveness
    not assessed
  • Certainty
    not assessed
  • Harms
    not assessed

Study locations

Key messages

  • Four studies evaluated the effects of relocating nests/eggs for artificial incubation on snake populations. Two studies were in Australia and one was in each of Japan and China.

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (4 STUDIES)

  • Reproductive success (4 studies): Two studies in Australia reported that 87% of carpet python eggs and 83% of brown tree snake eggs hatched successfully following artificial incubation. One study also reported that zero of 10 artificially incubated Oenpelli python eggs hatched. One study in Japan reported that 265 habu eggs hatched successfully following artificial incubation. One replicated, randomized study in China found that hatching success of artificially incubated stripe-tailed ratsnake eggs was lowest at the coolest and warmest temperatures tested.

BEHAVIOUR (0 STUDIES)

OTHER (1 STUDY)

  • Offspring sex ratio (1 study): One study in Japan reported that artificially incubated habu eggs produced offspring with an even sex ratio.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A study in 1982–1985 in Queensland, Australia (Charles et al. 1985) found that after bringing brooding female carpet pythons Morelia spilota and an Oenpelli python Morelia oenpelliensis and/or their egg clutches into captivity and incubating (artificially or with the female) the eggs, some carpet python eggs hatched successfully. From five female carpet pythons that were discovered with clutches of 7–23 eggs (clutch size for one snake not given), 21 of 23 and 5 of 7 eggs hatched successfully (one egg opened artificially), and some eggs from three other females also hatched successfully (number not given). None of the 10 eggs produced by an Oenpelli python hatched successfully. Brooding females that were discovered were brought into captivity along with their clutches, or in one case just the clutch was collected. Some eggs from one clutch were removed surgically. Eggs were incubated either in vermiculite or were left to incubate in the female’s coils (see paper for details).

    Study and other actions tested
  2. A study in 1981–1992 in the Okinawa Islands, Japan (Kamura & Nishimura 1993) found that artificially incubating habu Trimeresurus flavoviridis eggs resulted in some eggs hatching successfully. A total of 265 eggs hatched successfully (total number of eggs not given). When both hatchlings and un-hatched embryos were included, the ratio of females to males was equal (217:234). In 1981–1992, eggs from 62 female snakes were collected. They were incubated at 25–30°C in individual containers containing cotton or sphagnum moss Sphagnum sp., saturated with water.

    Study and other actions tested
  3. A replicated, randomized study in 1998 in a laboratory in Zhejiang, China (Du & Ji 2008) found that hatching success of artificially incubated stripe-tailed ratsnake Elaphe taeniura eggs was lowest at the coolest and warmest temperatures tested, and that incubation periods and hatchling morphology were also affected by incubation temperature. Hatching success was lower for eggs incubated at the coolest or warmest temperatures (22°C: 6 of 12, 50%; 32°C: 7 of 17, 41%) compared to eggs incubated at intermediate temperatures (24°C: 25 of 32, 78%; 27°C: 19 of 24, 79%; 30°C: 23 of 29, 79%). Incubation period decreased with increased temperatures from 102 days at 22°C to 51 days at 32°C. Five of seven morphological features were also affected by incubation temperature (see paper for more details). In 1998, thirteen captive-born gravid females were acquired and housed in a wire cage (200 x 80 x 80 cm) at 30°C. Eggs were incubated at 22, 24, 27, 30 or 32°C, with eggs from each clutch split evenly between temperatures. Eggs were incubated individually in covered plastic jars in vermiculite and water at a ratio of 1:2. Hatchlings were euthanized by freezing to -15°C to measure a 0range of morphological features.

    Study and other actions tested
  4. A study in 1984–1985 at Taronga Zoo, Sydney, Australia (McFadden & Boylan 2014) found that a wild-caught female brown tree snake Boiga irregularis laid eggs in captivity that following artificial incubation hatched successfully. Five of six eggs hatched successfully after an incubation period of 82 days. A gravid female was acquired in 1984 and laid a clutch of eggs soon after arrival. The clutch was incubated artificially but details on incubation conditions are not available.

    Study and other actions tested
Please cite as:

Sainsbury K.A., Morgan W.H., Watson M., Rotem G., Bouskila A., Smith R.K. & Sutherland W.J. (2021) Reptile Conservation: Global Evidence for the Effects of Interventions for reptiles. Conservation Evidence Series Synopsis. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

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Reptile Conservation

This Action forms part of the Action Synopsis:

Reptile Conservation
Reptile Conservation

Reptile Conservation - Published 2021

Reptile synopsis

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