Matt Betts, Tana EllisForest Ecosystems and Society, OSU

Collaborators: Joan Hagar, Brenda McComb, Kevin McGarigal, Jim Rivers

Thresholds in songbirds in relation to early seral forest at stand and landscape scales

(1939)

Area decrease = ~40%Mean patch size decrease = ~35% Kennedy and Spies 2005 Biol. Cons.

Historical and future ES

Paleo- &dendroecological studies + simulation modelging

‘Very open’ + ‘Patchy open’ = ~6% of historical landscape (Nokala & Spies 2005, Ecol. Apps.)

‘Early seral’ (<30 years) = 30% ~historical (Wimberly et al. 2000 Cons. Biol.)

‘Diverse early succession’ projected decline by 100% from HRV (Spies et al. 2007 Ecol. Apps.)

“Structurally and compositionally diverse early seral forest habitats are now the scarcest habitat in the region” (Thomas et al. 2006 – Cons. Biol.)

Orange-crowned warbler Rufous hummingbird

“Structurally and compositionally diverse early seral forest habitats are now the scarcest habitat in the region” (Thomas et al. 2006 – Cons. Biol.)

Stand Structure

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1. Which songbird species are associated with early seral broadleaf forest?

2. Is the occurrence of these bird species influenced by landscape composition?

3. Are there threshold levels of broadleaf in stands/landscapes?

4. Is habitat change ‘driving’ pop. declines?

Habitat variable ‘x’(Stand or landscape scale)

Pop

ulat

ion

size

/ occ

urre

nce/

den

sity

Betts and Villard 2009 – Cons. Targets.Betts et al. 2007 – Cons. Biol.

Authors of 14 studies contacted

- Klamath Bird Observatory (southern OR)- McGarigal & McComb (Coast range)- Hagar et al. (Coast range)- Fontaine (Biscuit fire)

Total N (after removing sites due to missing data) = 4375

4375 sample points127,164 bird detections 110 species

Gradient Nearest Neighbor (GNN) method for predictive vegetation

mapping

Regional forest survey+

Remote sensing data+

Imputation

= spatial data

Coastal Oregon

Oregon

IDNO TREE # SPECIES DBHCM HTM CC BHAGE TPHPLT

41034020 101 TSHE 39.116 24.384 4 83 2.617

41034020 116 CHLA 109.728 32.309 3 136 2.617

41034020 123 TSHE 55.880 39.319 3 103 2.617

41034020 129 PSME 200.152 58.826 3 913 1.000

41034020 133 PSME 66.802 40.843 3 99 2.617

41034020 316 TSHE 57.404 40.234 3 80 2.617

41034020 319 CHLA 105.664 45.110 3 244 2.617

41034020 320 CHLA 80.518 42.062 4 349 2.617

Attribute table (joined to ArcGIS grid)

Each pixel, or ArcGIS grid cell

% Broadleaf% Early seral broadleaf (<10 cm

dbh)Spatial extents: 150, 500, 2000 m

2 km

0.5 km

p = exp (β0 + β1x + β2(x – ψ)+) / 1 + exp (β0 + β1x + β2(x – ψ)+)

Segmented logistic regression:

Muggeo (2003) Statistics in Medicine

Threshold Detection

11/ 27 models showed threshold response

Pacific-slope flycatcher

Ranged broadly from 1.35 – 24.5%cc

Betts et al. Ecol. Apps. In Press

Positive response to early-seral broadleaf by 8/12 species

Coast Range

Klamath

LARGE REGIONAL VARIATION IN THRESHOLDS

GNN Species distribution performance:

Mean AUC = 0.83 ± 0.002 s.e.

Best spatial scale = 2000 m

Betts et al. Ecol. Apps. In Press

Positive influence of early and late seral broadleaf forest on many species

Population consequences may have already occurred

High variation in thresholds among species and regions

More research needed at stand and landscape scales (manipulations)

Stand Structure

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Tana Ellis and Matt Betts

Oregon State UniversityForest Ecosystems & Society

1. Does amount of hardwood cover within a stand influence

• occurrence of songbirds?• productivity of songbirds?

2. Are there threshold levels of hardwood within a stand?

• 28 Douglas-fir plantations of the central Oregon Coast Range

• Aged 5 to 9 years old

• Hardwood cover gradient 0-35%

6,013 total net captures Banded 4,639 Recaptured 837 53 species

White-crowned Sparrow n= 375

Swainson’s Thrush n= 375

Orange-crowned Warbler n= 370

MacGillivray’s Warbler n= 362

Willow Flycatcher n= 268

Need to take into account number of individuals (using rarefaction)

% Hardwood Cover

0 5 10 15 20 25 30 35

Sp

ecie

s R

ich

nes

s

0

5

10

15

20

25

30

35

Model Wi AIC Δ AIC THRESHOLD SE

Segmented 0.98 2.19 0.00 6.456 1.709

Linear 0.02 10.18 8.00 - -

Hardwood threshold at 6.7 % (SE=1.6)

Full model R2 = 0.45

Foliage gleaners=12.8% (SE=3.5)

Adult orange-crowned warbler HY (juvenile) orange-crowned warbler

β SE t P(Intercept) -2.09 0.06 -35.44 0.000Log(Hardwood) 0.08 0.03 2.84 0.009

β SE t P

(Intercept) -2.017 0.077 -26.143 0.000

logHWD 0.058 0.037 1.586 0.125AGE-HY -0.139 0.097 -1.429 0.165

logHWD:AGEHY 0.043 0.046 0.926 0.363

Migrant Bird Demography

Nest success Juvenile survival

Migratory survival

Adult survival

Overwinter survival

Faaborg et al 2010 Ecol. Monogr.

Does nest success = ‘habitat quality’?

Do conditions at the nest influence subsequent juvenile survival?

Nest success Juvenile survival

SWTH nest

SWTH nest

Fledgling SWTH with transmitter

What happened to fledgling #150.781?

22 juveniles tagged, 36% survived68% of mortality occurred within first

8 daysBest predictors:1. Hardwood during post-fledging

period (HR: 0.88 [95% CI: 0.76-1.00)2. Corticosterone in the nest (HR:

0.86 [95% CI: 0.71-1.04])

Summary

Bird distributions at stand and landscape scales are influenced by abundance of early seral forest

Demographic effects are apparentThis might be partly due to post-

fledging survival on the breeding grounds

Manipulative study (funded by USDA)

‘Top-down’ effects of birds on insect control

More extensive tests of thresholds

THANKS!