# Presentation: 300642

##  Example: Southern redback salamander, Plethodon serratus

- Terrestrial salamander in southern Appalachians
- Abundance is difficult to estimate
- Highly variable counts from natural cover or coverboard sampling
- Likely that p < 1

## “Site” Design

**Natural Cover Transect**

**Cover Boards**

- “Site” Design

_**Sampling Details**_
**39 “Sites” sampled**
**4 Years (1998-2001)**
**Sampled 5 times/year**

## Plethodon serratus Occupancy : Hypotheses

- Expect probability of occupancy influenced by previous disturbance history, **(dist).
- Expect temporal variation in occupancy and colonization probabilities due to variations in annual rainfall (declined 1999-2001 for April-June months).
- Expect temporal variation in detection probabilities due to yearly rainfall variations, *p (year **•), *or consistent yearly patterns of seasonal availability, *p (**• t). *

## Plethodon serratus Occupancy : Modeling

- Model parameterization: (***t*, ***t *)
- Candidate Models include combinations of:
- Occupancy (3 levels):
- (*•*) : Occupancy constant
- (*dist*): Occupancy varies by disturbance history
- (*year*): Occupancy varies by year
- Colonization (2 levels):
- γ(*•*): Colonization constant
*γ**(year): *Colonization varies by year
*D*etection (3 levels):
*p(**•**):  *Detection constant
*p (year **•):  *Detection varies due to yearly rainfall
*p(**• t):  *Detection varies due to seasonal availability within the 	sampling season

## p(• t) Model Results: Occupancy & Detection

*p(• t)* Model Results: Occupancy & Detection

**K = number of parameters. For models with ***Ψ*(*dist),** ***the first occupancy estimate is for undisturbed sites, followed by disturbed site estimate in parentheses. Only detection probabilities for first & last sample reported.**

## p(• t) Model Results: Colonization

*p(• t)* Model Results: Colonization

**K = number of parameters. *****w ***** = Akaike weight, evidence (probability) the given model is the ‘best’**

## p(year •) Model Results: Occupancy & Detection

| Compare Models 
with p(year •) | ∆
AIC |    Ψ
1998 |   Ψ
1999 |   Ψ
2000 |    Ψ
2001 |  p
‘98 |  p
‘99 |  p
‘00 |  p
‘01 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Ψ(dist)γ(•)p(year •) | 86.7 | 0.97
(0.42) | 0.97
(0.42) | 0.97
(0.42) | 0.97
(0.42) | 0.34 | 0.61 | 0.55 | 0.41 |
| Ψ(dist)γ(year)p(year •) | 88.5 | 0.96
(0.44) | 0.96
(0.44) | 0.96
(0.44) | 0.96
(0.44) | 0.34 | 0.61 | 0.55 | 0.40 |
| Ψ(•)γ(•)p(year •) | 101.9 | 0.81 | 0.81 | 0.81 | 0.81 | 0.34 | 0.61 | 0.55 | 0.41 |
| Ψ(year)γ(•) p(year •) | 107.4 | 0.84 | 0.82 | 0.80 | 0.81 | 0.34 | 0.61 | 0.55 | 0.41 |
| Naïve Estimates |  | 0.579 | 0.821 | 0.821 | 0.744 |  |  |  |  |

**K = number of parameters. For models with ***Ψ*(*dist),** ***the first occupancy estimate is for undisturbed sites, followed by disturbed site estimate in parentheses.**** **

## p(year •) Model Results: Colonization

| Compare Models 
with p(year •) | 
w | ∆
AIC | 
K |    γ
1998 |   γ
1999 |   γ
2000 |
| --- | --- | --- | --- | --- | --- | --- |
| Ψ(dist)γ(•)p(year •) | 0.00 | 86.7 | 7 | 0.21 | 0.21
 | 0.21 |
| Ψ(dist)γ(year)p(year •) | 0.00 | 88.5 | 9 | 0.24 | 0.27 | 0.03 |
| Ψ(•)γ(•)p(year •) | 0.00 | 101.9 | 6 | 0.19 | 0.19 | 0.19 |
| Ψ(year)γ(•) p(year •) | 0.00 | 107.4 | 9 | 0.15 | 0.15 | 0.15 |
| Naïve Estimates |  |  |  | 0.28 | 0.05 | 0.00 |

**K = number of parameters. *****w ***** = Akaike weight, evidence (probability) the given model is the ‘best’**

## p(• •) Model Results: Occupancy & Detection

| Compare Models 
with p(• •) | ∆
AIC |    Ψ
1998 |   Ψ
1999 |   Ψ
2000 |    Ψ
2001 |  p |
| --- | --- | --- | --- | --- | --- | --- |
| Ψ(dist)γ(•) p(• •)
 | 102.9 | 0.95
(0.42) | 0.95
(0.42) | 0.95
(0.42) | 0.95
(0.42) | 0.50 |
| Ψ(dist)γ(year)p(• •)
 | 105.0 | 0.94
(0.44) | 0.94
(0.44) | 0.94
(0.44) | 0.94
(0.44) | 0.50 |
| Ψ(•)γ(•) p(• •)
 | 110.5 | 0.78 | 0.78 | 0.78 | 0.78 | 0.51 |
| Ψ(year)γ(year) p(• •) | 116.6 | 0.64 | 0.83 | 0.82 | 0.76 | 0.52 |
| Ψ(year)γ(•) p(• •)
 | 121.4 | 0.70 | 0.76 | 0.79 | 0.80 | 0.51 |
| Naïve Estimates |  | 0.579 | 0.821 | 0.821 | 0.744 |  |

**K = number of parameters. For models with ***Ψ*(*dist),** ***the first occupancy estimate is for undisturbed sites, followed by disturbed site estimate in parentheses. **

## p(• •) Model Results: Colonization

| Compare Models 
with p(• •) | 
w | ∆
AIC | 
K |    γ
1998 |   γ
1999 |   γ
2000 |
| --- | --- | --- | --- | --- | --- | --- |
| Ψ(dist)γ(•) p(• •)
 | 0.00 | 102.9 | 4 | 0.21 | 0.21 | 0.21 |
| Ψ(dist)γ(year)p(• •)
 | 0.00 | 105.0 | 6 | 0.62 | 0.25 | 0.00 |
| Ψ(•)γ(•) p(• •)
 | 0.00 | 110.5 | 3 | 0.23 | 0.23 | 0.23 |
| Ψ(year)γ(year) p(• •) | 0.00 | 116.6 | 8 | 0.62 | 0.25 | 0.00 |
| Ψ(year)γ(•) p(• •)
 | 0.00 | 121.4 | 6 | 0.32 | 0.32 | 0.32 |
| Naïve Estimates |  |  |  | 0.28 | 0.05 | 0.00 |

**K = number of parameters. *****w ***** = Akaike weight, evidence (probability) the given model is the ‘best’**