Robbins Butte Wildlife Management Area
Maricopa County, Arizona

Introduction

This wildlife area managed by the Arizona Game and Fish Department is 680 hectares (1681 acres) in size and includes several diverse habitats. It is bounded on the north and west by the remnants of the Gila River where there is some open, ponding water with marshy cattails along side. Extensive areas adjacent to the river are broad, almost impenetrable thickets of deciduous tamarisk (a.k.a. salt cedar) variously interspersed with native willows, cottonwoods and mesquites. Back from the tamarisk thickets are areas of occasional inundation - every decade or so the Gila River overflows. Here there are large mesquites, blue palo verdes, athel trees (an evergreen, non-native tamarisk relative) and gray thorn bushes. The ground water is not far below the surface and occasional patches of salt-encrusted soil can be found.

View of Robbins Butte from the south. The gray-green shrubs are Allscale Saltbush.

Another wide boundary of partly saline or alkaline soil occurs back from areas with larger trees. Here the soil is very fine textured sand and silt with clays and quite deep. Flooding is infrequent and the water table is further yet below the surface. Reaching almost 100% of the shrub cover is Allscale Saltbush. These ashy-green shrubs are about 1½ meters tall. Interspersed with the saltbush are darker green shrubs with fleshy leaves, purple flowers and red berries (in season), Fremont Thornbush.

Finally the rest of the area away from the river up to the boundary of Buckeye Hills Park is mostly creosote and white bursage desert with a few ironwoods, wolfberry, foothill palo verde and cacti mixed in. Still the soil is mostly deep encouraging the presence of burrowing animals.

Area Map on Google

Directions: From the Phoenix area drive west on I-10, then exit south (car symbol) on SR-85. The road into the wildlife area is clearly marked on west side of highway. Take gravel road west towards Robbins Butte. Just south of Robbins Butte is a Maricopa County Park, Buckeye Hills. The blue thumb is location of Powers Butte, part of this wildlife area. The green thumb in lower left indicates location of the Gila Bend Mountains.

Common Birds

This list is based on two field trips (Jan 13 & Mar 8, 2008):

1. White-crowned Sparrow -- F,W,Sp -- a winter visitor from the north. Feeds on seeds, berries and sprouting seeds.
2. Black-tailed Gnatcatcher -- Polioptila melanura -- S, F,W,Sp -- all year resident. forages in small trees + shrubs
3. Costa's Hummingbird -- Calypte costae -- S,F,W,Sp -- more common late winter/spring. Favors Lycium fremontii flowers.
4. Mallard -- Anas platyrhynchos -- S,F,W,Sp -- along river and more common in winter
5. Northern Mockingbird -- Mimus polyglottos -- year round resident
6. Snowy Egret -- Egretta thula -- year round but more common in warm months
7. Gambel's Quail -- Callipepla gambelii - year round resident
8. Osprey -- F,W,Sp -- present late fall to early spring along river
9. Northern Harrier -- F,W,Sp -- present late fall to early spring over open habitats
10. American White Pelican -- F,W,Sp -- uncommon, but readily seen when they soar above river

Black-tailed Gnatcatcher photographed by Robert Shantz.

Reptiles and Amphibians

1. Side-blotched Lizard -- active even in January

When temperatures are cool side-blotched lizards will emerge and bask in the sunshine. Notice the dark splotch on the flank immediately behind the first pair of legs.

Shrubs and Trees

1. Allscale Saltbush -- Atriplex polycarpa
2. Tamarisk;Salt Cedar -- Tamarix pentandra
3. Velvet Mesquite -- Prosopis velutina
4. Fremont Thorn Bush -- Lycium fremontii
5. Blue Palo Verde -- Parkinsonia florida
6. Creosote Bush -- Larrea tridentata
7. Catclaw Acacia -- Acacia greggii
8. Graythorn -- Ziziphus obtusifolia
9. Desert Seepweed -- Suaeda moquinii
10. Fremont Cottonwood -- Populus fremontii
11. Arrow Weed -- Pluchea sericea
12. Desert Mistletoe -- Phoradendron californicum
13. Foothills Palo Verde; Yellow Palo Verde -- Parkinsonia microphylla
14. Anderson Thornbush;Wolfberry -- Lycium andersonii
15. Saguaro Cactus -- Carnegiea gigantea
16. Desert Ironwood -- Olneya tesota
17. Four-winged Saltbush -- Atriplex canescens
18. Buckhorn Cholla -- Cylindropuntia acanthocarpa -- other chollas scarce
19. Virgin's Bower -- Clematis drummondii
20. White Ratany -- Krameria grayi
21. White Bursage -- Ambrosia dumosa -- by far the most abundant bursage
22. Brittlebush -- Encelia farinosa
23. Graham's Pincushion Cactus -- Mammillaria grahamii
24. Lance-leaf Ditaxis -- Argythamnia lanceolata
25. Engelmann Hedgehog Cactus -- Echinocereus engelmannii -- very scarce

White Flowers

1. California Mustard -- Guillenia lasiophylla
2. Chaenactis fremontii
3. Emory Rock Daisy -- Perityle emoryi
4. White Easter-bonnets -- Antheropeas lanosum
5. Comb Bur -- Pectocarya platycarpa
6. Narrow-leaf Popcorn Flower -- Cryptantha angustifolia
7. Desert Chicory -- Rafinesquia neomexicana
8. Browneyes -- Camissonia claviformis
9. Wingnut Cryptantha -- Cryptantha pterocarya

Browneyes

Desert Bladderpod

Yellow Flowers

1. Brittlebush -- Encelia farinosa
2. Sahara Mustard;Asian Mustard -- Brassica tournifortii
3. Bladderpod -- Lesquerella sp.

Orange Flowers

1. California Poppy -- Eschscholzia californica
2. Orange Fiddleneck -- Amsinckia intermedia
3. Sand Pygmy-weed -- Crassula connata
4. Desert Rose Mallow -- Hibiscus coulteri

Purple Flowers

1. Purple Owl's Clover -- Castilleja exserta
2. Red-stemmed Fillaree -- Erodium cicutarium

Blue Flowers

1. Phacelia distans
2. Notch-leaved Phacelia -- Phacelia crenulata
3. Lupine -- Lupinus sparsiflorus

Lupine

Green Flowers

1. Indianwheat; Woolly Plantain -- Plantago ovata
2. Lineleaf Whitepuff -- Oligomeris linifolia