Table 1 Parameters of the VORTEX model used to simulate Crested Ibis population growth

# of iterations

# of times the simulation is run

500

# of years

# of years the population is modeled

50 (2019‒2068)

Extinction definition

How extinction is defined in the model

Only one sex remains

# of populations

# of populations to be modeled

1

Inbreeding depression

The level and effect of inbreeding depression

Yes

Lethal equivalents

The severity of inbreeding depression

0

EV concordance of reproduction and survival

The concordance between reproduction and survival in different populations

Not applicable—only 1 population modeled

Dispersal rate

The rate of dispersal between populations

Not applicable—only 1 population modeled

Reproductive system

The mating system

Monogamy (Zhai et al. 1994)

Age at 1st reproduction in females

Age at which females begin breeding

2 (Zhai et al. 1994)

Age at 1st reproduction in males

Age at which males begin breeding

2 (Zhai et al. 1994)

Maximum age at reproduction

Age of females/males when breeding ceases

15 (Yu et al. 2007)

Maximum # of progeny produced/year

Maximum # of offspring produced by females each year

5 (Zhai et al. 2001)

Sex ratio at birth

Sex ratio of offspring at hatching

1:1

Density dependence of reproduction

The relationship between reproduction and population density

Yes

P(0)

% adult females breeding at low density

35.70% (Additional file 1: Table S1)

P(K)

% adult females breeding at carrying capacity

50.00% (estimates)

A

Allee parameter

0 (Chen 2018)

B

Steepness parameter

2 (Ralls et al. 1988)

Proportion of adult females breeding

The percentage of adult females that breed each year

(35.7 − ((35.7 − 50) × ((N/K)²))) × (N/(0 + N))

EV in % breeding

EV in % of adult females breeding each year

10% set as default

Distribution of # of offspring/female

Statistical distribution characterizing the # of offspring produced

Specify exact distribution

1. Offspring

2. Offspring

3. Offspring

4. Offspring

5. Offspring

Percentages of females with certain numbers of offspring

1.25%

10.00%

32.50%

53.75%

2.50% (Additional file 1: Table S2)

Female mortality

Mortality rates of females, specified for three age classes (0–1, 1–2, and 2+) by the mean and SD

For baseline: 0–1, 45.1%; 1–2, 15.1%; 2+, 5.9% (Wang 2015); SD set at 10% of the mean as default

Male mortality

Mortality rates of males, specified for three age classes (0–1, 1–2, and 2+) by the mean and SD

Identical to female mortality

Number of catastrophes

Each type of catastrophe is implemented separately and occurs independently

2

Catastrophe frequency

Frequency of catastrophes affecting the population

Catastrophe 1: 14%

Catastrophe 2: 15%

Catastrophe severity

Reduction in survivorship/reproduction as a result of the catastrophe

Catastrophe 1: reduction in survivorship/reproduction: 0.1/0.1

Catastrophe 2: reduction in survivorship/reproduction: 0.1/0.1

Mate monopolization

% of adult males breeding/year

28.11% (Additional file 1: Table S1)

Initial population size

The number of individuals at the beginning of the simulation

150 (population size in 2018)

Age distribution of initial population

Distribution of individuals by age at the beginning of the simulation

Stable age distribution

Carrying capacity

The carrying capacity of the environment

420 (estimates)

Harvest

Whether individuals were removed from the population

No harvest

Supplementation

Whether individuals were added to the population

No supplementation