Questionnaire


Reproduction

Hatching probability (F1)

If tara iti eggs are incubated artificially, do you expect the hatching probability to be different from that of naturally incubated eggs (0.6 ± 0.11 since 2010)? If so, what do you believe that value will be?



Expert Minimum Plausible Most Likely Maximum Plausible Confidence
FR 60.0 70 85.0 86
GB 50.0 70 100.0 100
JZ 36.9 60 79.3 96
MB 75.0 85 100.0 90
NR 50.0 80 90.0 95
RI 50.0 75 100.0 100
TI 36.9 60 79.3 100

Comments

Artificial incubation
  • MB: Based on the results of the eggs artificially incubated in the last few years, I think there is a very high probability that the (viable) artificially incubated eggs hatch successfully. And that’s a higher probability than for the naturally incubated eggs, as the later are subject to predation and extreme environmental events
  • FR: Hatching rates of AI eggs has really improved, and eggs in captivity are not subject to any predation pressures but there are still intrinsic factors like early embryo death and infertiity

  • GB: My understanding is that if eggs are taken soon after laying they are more likely to die which would be a negative influence. If they are not taken they run the risk of predation, abandonment and weather events which have been mitigated by management but not eliminated. The main reason I expect an increase in hatch rate is that viable eggs will deliberately be selected and those fathered by infertle birds or with early embryo death would not be taken into captivity.

    I also think that this is primarily a data question rather than a matter of belief and the data to answer it, at least to point already exist.
  • RI: - In some years, hatching success could be 1.0 as evidenced by past efforts. - Eggs taken from known fertile pairs. - Reduction of threats in captivity compared to the wild, e.g. predation, environmental factors. - Smaller sample sizes combined with hatching failure of even one egg will influence the value in any one year. - Method for incubation well developed and refined over the past five years.


Fledging probability (F1)

For captive reared chicks, do you expect survival until fledging to be different from that of wild reared chicks (0.58 ± 0.05 since 2010)? If so, what do you believe that value will be?



Expert Minimum Plausible Most Likely Maximum Plausible Confidence
FR 65 75 85.0 88
GB 50 75 100.0 100
JZ 47 58 68.2 85
MB 85 90 100.0 90
NR 52 80 85.0 95
RI 50 75 100.0 100
TI 65 75 85.0 100

Comments

Artificial incubation
  • FR: Last 2 years have had 100% survival but with bigger cohorts likely to be some losses
  • GB: We do not know all the reasons that chicks die in the wild. Some are predated or pecked, some almost certainly starve. These things should be avoided in captivity so you could often get 100% survival or close to it. To balance this there are risks of damage from the cages and hardware in the cages and also an increased disease risk. There is also the likelihood of treatment and recovery in captivity so I have pushed the value upward.
  • RI: - Survival until fledging has increased from 0.25 in 2022/23, 1.0 in 2023/24 and 2024/25. - Max. 1.0, but assuming best possible outcomes in any one year. - Reduction of threats in captivity compared to the wild, e.g. predation, environmental factors. - Small sample sizes so mortality of one individual will influence value in any one year. Survival could be influenced by individual bird health.
  • MB: Based on the results of the chicks hand-reared in the last few years, I think there is a very high probability that they reach fledging age. And that’s a higher probability than for the naturally reared chicks, as the later are subject to predation and extreme environmental events
  • TI: Anticipate that survival pe-fledging for captive chicks is higher as methodology developed to rear and feed is good, access to medical intervention if required and reduction of risk associated with predation, storms and other environmental factors.


Clutch size (F1)

For a captive reared tara iti, female, do you expect her average clutch size to be different from that of wild-hatched females (1.71 ± 0.45 since 2010)? If so, what do you believe that value will be?



Expert Minimum Plausible Most Likely Maximum Plausible Confidence
FR 0.81 1.71 2.61 100
GB 0.81 1.71 2.61 100
JZ 0.81 1.71 2.00 95
MB 0.81 1.71 2.61 100
NR 0.00 1.71 2.40 95
RI 0.81 1.71 2.61 100
TI 0.81 1.71 2.61 100

Comments

AI females
  • RI: Potentially, but dependent on female behaviour (to be tested). Assuming clutch size influenced by prey availability / caloric intake, if females (or mates) supplement from feeding trays, there is a possibility that average clutch size may be larger compared with wild females. Without supplementation, average clutch likely to be the same.

  • GB: If a tara-iti has survived for nearly two years or more in the wild I believe she woud effectively be a wild tara iti and subject to the same constraints.

    If she remained in captivity with an improved food supply, or was supplementally fed in the wild she might do better.


Hatching probability (F2)

For a captive reared tara iti, female, do you expect the hatching probability of her eggs to be different from that of eggs laid by wild-hatched females (0.6 ± 0.11 since 2010)? If so, what do you believe that value will be?



Expert Minimum Plausible Most Likely Maximum Plausible Confidence
FR 36.9 60 79.3 100
GB 36.9 60 79.3 100
JZ 36.9 60 79.3 95
MB 36.9 60 79.3 100
NR 0.0 60 79.3 95
RI 36.9 65 79.3 100
TI 36.9 55 79.3 100

Comments

AI females
  • RI: Eggs selectively chosen from known fertile/productive pairs, thus, increasing the probability of egg fertility compared with the wild population. However, eggs from captive-reared female breeding in the wild still subject to same extrinsic factors (storms, predators, human disturbance) and therefore hatching probability not likely to be considerably different. Assumes no difference in breeding success of first time breeders from captive and wild populations.

  • GB: Any tara-iti old enough to breed should be equally capable, more or less, to function in the wild.

    There is evidence of food limitation reducing the number and viability of eggs laid and her mate is also important here partly through the control of a feeding territory and also by providing all of er food in the week or so prior to laying.


Fledging probability (F2)

For a captive reared tara iti, female, do you expect the probability of fledging for her chicks to be different from that of chicks reared by wild-hatched females (0.58 ± 0.05 since 2010)? If so, what do you believe that value will be?



Expert Minimum Plausible Most Likely Maximum Plausible Confidence
FR 47 55 68.2 61
GB 47 58 68.2 100
JZ 47 58 68.2 95
MB 47 58 68.2 100
NR 0 58 68.2 95
RI 47 58 68.2 100
TI 40 50 68.2 87

Comments

AI females
  • FR: Think a slight dip is possible, possile that provisioning of young may not be as good as wild reared parents
  • GB: I suspect any tara iti old enough to breed would be equally capable. It is possible that antipredator behaviour is learned from parents and a captive reared bird may not be up to scratch but also remember that the male is a vigorous defender too.
  • RI: Assumes no difference in breeding success for first-time breeders in wild versus captive birds.


Survival

Juvenile survival

For a captive reared tara iti, do you expect juvenile survival (survival to 1 year) to be different from that of wild-hatched individuals (0.69 ± 0.07 since 2010)? If so, what do you believe that value will be?



Expert Minimum Plausible Most Likely Maximum Plausible Confidence
FR 0.35 0.5 0.7 100
GB 0.00 40.0 75.0 100
JZ 30.00 50.0 70.0 85
MB 0.00 50.0 69.0 50
NR 40.00 63.0 82.9 95
RI 0.25 60.0 75.0 100
TI 54.50 50.0 82.9 100

Comments

Artificial incubation
  • FR: lower survval of captive reared young is fairly typical across speceis

  • GB: Survival to one year is extremely variable in wild tara iti and also mysterious because we don’t yet know where they go, what they do or why they die.

    One reason I think captive born juveniles are more likely to die is that wild families remain together for perhaps their first month on the Kaipara. During this time parents may still feed their young which would be important if fishing is poor in some seasons and it is also plausible that they learn where best to feed and how to do it.

    The otheer reason is that they may be relatively naive to predators and, if roosting alone, may choose unsafe sites, especially if they roost alone or in a flock of only captive reared birds.

    Association with parents may anchor their offspring to the harbour more than we have seen with the captive birds this last season so they may be exposed to less risk from exposure to weather and poor food supply in unfamiliar sites.

    It is also possible that in poor food years captive reared juveniles will start their independence stronger and healthier than wild juveniles.
  • MB: I think the survival rate of hand reared birds probably would be lower than that of the parent reared birds, as the first lack the parental care and teaching
  • TI: Anticipate survival to be lower without parental support. However, recent captive survival was higher than anticipated (24/25)

  • RI: Reduced survival compared with wild-reared birds due to a lack of parental guidance and supplementation (after leaving Te Arai). Extended periods of post-fledging dependence not available to captive-reared birds.

    In Damara Tern, fledging dependency extends for up to two and a half months (Williams & Myer 1986 in Braby et al. 2011). Specialised feeding technique (plunge diving) – a skill that requires considerable time to perfect and explains the extended post-fledging dependency. But noting captive-reared birds supplement feed from pools for at least several weeks post-fledging.

    Rate highly influenced by dependent on sample size.


Immature survival

For a captive reared tara iti, do you expect immature survival (survival between 1 and 2 years) to be different from that of wild-hatched individuals (0.92 ± 0.06 since 2010)? If so, what do you believe that value will be?



Expert Minimum Plausible Most Likely Maximum Plausible Confidence
FR 75.0 85.0 95 70
GB 79.6 92.2 99 100
JZ 79.6 92.2 99 90
MB 75.0 92.0 100 100
NR 79.6 92.2 99 100
RI 79.6 92.2 99 100
TI 79.6 92.2 99 100

Comments

Artificial incubation
  • MB: I think the immature survival of hand reared birds could be very similar to that of parent reared ones as during the first year any bird not fully fit to live in the wild would have already died.
  • FR: lack of parental support in initial year may have some carry over i effects - sligtly less prepared than wild counterparts
  • GB: Any tara iti that has survived for one year in the wild must be equally competent and capable of surviving another.


Adult survival

For a captive reared tara iti, do you expect adult survival (2+ years old) to be different from that of wild-hatched individuals (0.9 ± 0.03 since 2010)? If so, what do you believe that value will be?



Expert Minimum Plausible Most Likely Maximum Plausible Confidence
FR 84.3 89.5 94.7 100
GB 84.3 89.5 94.7 100
JZ 84.3 89.5 94.7 90
MB 84.3 89.5 94.7 100
NR 84.3 89.5 94.7 100
RI 84.3 89.5 94.7 100
TI 84.3 89.5 94.7 100

Comments

Artificial incubation
  • GB: Any tara iti, captive or wild born, that is old enough to breed must be reasonably competent to have lasted at least two years and I think it would have a good chance of surviving longer.