Gray Vireos: A Coda

Gray Vireo, photo copyright & courtesy of Deb Vogt

Thanks, everyone, for the Gray Vireo emails and all the location info!  (Just so you know – I really use that location information, entering them into one of my databases – next year’s map will be including all of these new sites!) 

I wanted to share a few photos Deb Vogt sent me – in June, she found a pair of Gray Vireos and their nest down in southern Nevada.  She thought they were feeding a fledgling deep in the tree – one parent “cussed her out”, while the other sang.  I hadn’t seen a Gray Vireo nest before, so I was happy to finally get to see a picture, at least!  Thanks, Deb!

Happy birding,

Jen

Gray Vireo nest, copyright & courtesy of Deb Vogt

Gray Vireos: A Request To Keep Your Birding Eyes Peeled

An NBC point where Gray Vireos recorded

Gray Vireos are a favorite of mine (though, to be honest, there’s hardly a bird on Nevada’s species list I haven’t said that of, at one time or another!), breeding primarily within pinyon-juniper habitats in Nevada; juniper appears to be particularly important.  They’re also a species of conservation concern within the state, and Nevada supports an estimated 20% of the global population [1].

Another Gray Vireo location

These guys are ones I enjoy mapping, and every year, it seems I generate a “hmmm, let’s see what the data look like this year” map.   This morning, I was going through some data collected in the Pine Nuts earlier in the year, and saw that we have three more Gray Vireo records there.  So you can tell what’s coming next: my thoughts turned vireo-ward!  During the afternoon’s caffeine break, I dove into GIS, played with the data, and churned out the following maps.  The first one is of all our Gray Vireo locations recorded during the Nevada Bird Count (NBC) and Atlas [2] surveys, with confirmed breeding locations broken out.  

And yet another one!

You can see during the Atlas years all of the locations are down south and within the eastern mountains of the state.  During the past 10 or so years of the Nevada Bird Count, we’ve also been accumulating records within central/western Nevada, including along the Nevada/California border, north of the Mojave Desert.  The border locations are mostly from surveys completed during and after 2009.  The second map is of all of our NBC points and Atlas locations, for reference (including incidental locations). 

On to the request:  we don’t yet have confirmed breeding records for these northern/western locations, and I’m particularly interested in confirming the breeding status along the Nevada-California border.  We have probable breeding records in the north/central portion of the state, but the highest evidence we’ve so far recorded for the border mountains is singing and possible pairs.  If you find yourself hanging out in pinyon-juniper in May/June/July, keep your eyes and ears peeled for these guys -- and if you confirm breeding (e.g., carrying nesting material, nests/eggs/nestlings, parents carrying food/fecal sacs, recently-fledged juveniles), please do let me know!  … Then I’ll have a good excuse to make up another map!

Happy birding!

Jen

Gray Vireo Atlas and Nevada Bird Count locations, with confirmed breeding

Nevada Breeding Bird Atlas and Nevada Bird Count survey locations, including incidentals

[1]   Great Basin Bird Observatory. 2010.  Nevada Comprehensive Bird Conservation Plan, ver. 1.0.  Great Basin Bird Observatory, Reno, NV. 

[2]  Floyd et al. 2007.  Atlas of the Breeding Birds of Nevada.  University of Nevada Press, Reno.

Surveying Birds along the Lower Colorado River, 2013

The spring of 2013 was an amazing field season on the Lower Colorado River.  This past season we had our largest crew on record, with 17 people!    We were very lucky to have a group of highly qualified ornithologists.  The first month of the season, as always, was spent sharpening our bird skills, learning our survey methods, as well as clearing trails to our survey plots.  Driving routes and trails need to be established to all our bird plots that were randomly selected for the season.  This is no easy task considering this past year we surveyed approximately 250 plots.  Trail clearing can be rough work, but it definitely helps the crew to bond as we spend the entire month working together. Once the first month is finished up, the crew splits off to their respective field sites and surveys begin.   This year we had four field houses spanning the length of our study area from southern Nevada to the international boundary with Mexico. 

Photo by Alicia Arcidiacono

To survey for birds, we use an area search or spot-mapping survey approach.  For this method, our surveyors are given an aerial image of their survey plot superimposed with a UTM grid. The surveyor walks systematically passing within 50m of all points on their survey plot.  During this time the surveyor records all birds seen and heard on their maps and any evidence of breeding. Surveys begin at, or a half hour before, sunrise and usually last several hours. 

The crew had a fantastic season recording approximately 200 different species of birds. Additionally over 21,000 individual locations of birds were mapped and entered into GIS.  Our crew also documented a large number of rarities, including the first breeding record of a Nutting’s flycatcher in the US.  We also recorded Rufuous-backed Robin, Palm Warbler, and Baltimore Oriole; all of which are rare birds within our study area.   

In addition to birds, other wildlife species were plentiful in our study area. We observed bobcats, mountain lions, several species of rattlesnake, javelina, badgers, skunks, bighorn sheep, and much more.  Throughout this past season we had many great adventures and made some lasting friendships.  With another season wrapped on the LCR, I am left in disbelief how quickly the time passed.  Thanks crew of 2013 for making it one of our best seasons on record!  Looking forward to 2014!   

- Dawn

Warm Springs Natural Area Species List, September 28 - October 2

Warm Springs Natural Area, from near the entrance gate

So here’s the list of the birds recorded during my surveys at Warm Springs.  (The surveys were randomly located on the property, not designed to hit hot spots.)  I described a few of my highlights here.  The most commonly-recorded species were (in order): White-crowned Sparrow, Gambel’s Quail, House Finch, Red-winged Blackbird, Abert’s Towhee, Mourning Dove, Turkey Vulture, Western Scrub-Jay, and Yellow-rumped Warbler.  For comparison, my highlights from the 2012 surveys are here. 

1. Gambel's Quail
2. Turkey Vulture
3. Sharp-shinned Hawk
4. Red-tailed Hawk
5. American Kestrel
6. Virginia Rail
7. Eurasian Collared-Dove
8. Mourning Dove
9. Greater Roadrunner
10. Belted Kingfisher
11. Lewis's Woodpecker
12. Red-naped Sapsucker
13. Red-naped Sapsucker x Red-breasted Sapsucker
14. Ladder-backed Woodpecker
15. Northern Flicker
16. Say's Phoebe
17. Vermilion Flycatcher
18. Loggerhead Shrike
19. Cassin's Vireo
20. Western Scrub-Jay
21. Common Raven
22. Barn Swallow
23. Verdin
24. Bushtit
25. Cactus Wren
26. Rock Wren
27. Bewick's Wren
28. House Wren
29. Marsh Wren
30. Ruby-crowned Kinglet
31. Blue-gray Gnatcatcher
32. Black-tailed Gnatcatcher
33. Northern Mockingbird
34. Crissal Thrasher
35. European Starling
36. Phainopepla
37. Orange-crowned Warbler
38. Common Yellowthroat
39. Yellow-rumped Warbler
40. Spotted Towhee
41. Abert's Towhee
42. Brewer's Sparrow
43. Lark Sparrow
44. Unidentified “Sage” Sparrow
45. Song Sparrow
46. Lincoln's Sparrow
47. White-crowned Sparrow
48. Summer Tanager
49. Red-winged Blackbird
50. Western Meadowlark
51. House Finch
52. Lesser Goldfinch

Happy birding!

Jen

Escape!

Whew.  In late September, I hacked apart the chain tethering me to my laptop and the joys of proofing data, and headed southward to the Warm Springs Natural Area for a few days to collect some data.  Free at last!  I’m still in the process of getting the survey data entered, so I’ll leave the full species list for a later post, but I thought I’d share some highlights and a few photos.  I didn’t see anybody particularly unexpected, but one of my favorite things in wildlife biology is delving into what is expected, where, and why!

• Western Scrub-Jays.  My goodness, the Scrub-Jays.  We tend to run into a few in mid-April, but we hadn't had any fall records in our dataset until this visit.  Plus Flickers.  They were EVERYWHERE, and apparently had just arrived en masse … not to mention a Lewis’s Woodpecker or two.

Red-naped x Red-breasted Sapsucker

• I was really excited to see sapsuckers: Red-naped and Red-naped x Red-breasted hybrids.  So far, in my September forays to Warm Springs, several of the Red-naped/Red-breasted/hybrid Sapsuckers have been young-of-the-year, and at least half have been hybrids.  Has anyone else noticed this pattern in that part of the state/at that time, or is it just a function of my small sample size?  I’d be really interested to hear, either way!

• Not that these guys are that uncommon, but I enjoyed my 4-wren day, with Bewick’s Wrens, Marsh Wrens, House Wrens, and a Cactus Wren (!) hanging out in the riparian area within a space of about 300 meters.  It's not that Cactus Wrens are unknown from the area, but I have to admit that I was a little startled to have one poke its head out from the palm fronds, rasping its song.

• Summer Tanagers.  Any day I see a Summer Tanager is a good day in my book, and I had 3 days of them pitucking from among the palm fronds and cottonwood leaves.

The Bee Nest Tunnels are these dark spots on the ground surface

• The Phainopeplas are back, “hoyting” from the top of mesquites.

• A particularly fun discovery was a colony of native ground bees: maybe alkali bees?  There is an alfalfa field only a couple hundred meters away.  SO cool.  [As an aside, if you’re interested in books on pollinators, Stephen Buchmann and Gary Paul Nabhan’s The Forgotten Pollinators is one of my favorites.] 

• I found a few unidentified Sage Sparrows (but nothing like the winter numbers) darting into the shrubbery, thwarting my attempts to determine whether they were Bell’s or Sagebrush Sparrows!

• Lots of Sharp-shinned Hawks, too.  I tried to get some photos, but ended up with some fantastic pictures of branches instead.

• Warbler-wise, it’s a little late, so I was limited to Yellow-rumped (all Audubon’s), Orange-crowned, and Common Yellowthroats.  Again, I tried to get some photos of the Yellow-rumps, and ended up with yet more pictures of branches!

Lincoln's Sparrow

• By far the most abundant species I found, though, was the White-crowned Sparrow, who were packed into the former pastures now filled with sunflowers.  There were so many of them, and they were moving around so much, it was difficult to pick out the occasional Lincoln’s and Song Sparrows.  House Finches were also found here in large numbers, but at least they perched on the tops of the sunflowers, making them easy to see; plus they called almost incessantly.  The Lincoln’s and Song Sparrows were mostly on the ground, where they alerted me to their presence by the scratching sounds as they foraged - along with the occasional call note.

• I watched a Loggerhead Shrike manipulate a large green grasshopper with its beak, finally impaling it onto the broken stub of a mesquite branch.

• Last but not least: Monarch butterflies.  I didn’t see nearly as many of them this year as I did in 2012 (from what I understand, last year was a particularly good year for them in Nevada), but I saw quite a few scattered through the area.

Well, that’s it for now, I think.  I’ll try to get the rest of the data finished up soon, so I can put up the full species list.

Happy birding!
Jen

Sagebrush and Bell's (canescens) Sparrows

In case you hadn't seen Peter Pyle's writeup on distinguishing Sagebrush and (canescens) Bell's Sparrows in fresh plumage (fall/early winter; the primary period when their ranges will be overlapping), you can find it here. What is particularly useful is that the writeup contains photos of study specimens from Berkeley's Museum of Vertebrate Zoology; most of these photo sets are comparing fresh plumage, but a few are of worn plumage.

Definitive Prebasic Molt (according to the Sage Sparrow Birds of North America (BNA) account) begins in June, finishing by mid-September (whether anyone has looked at timing differences etc by subspecies, I don't know). Records of arrivals of Sagebrush Sparrows onto territories range from late February to late April. In Mono County, canescens begins nest building in early March, and the final nests started in mid-late June. Southern populations of canescens may start up earlier (I haven't seen any data on it) but I suspect will at least skew to the early side of that range. At any rate, you can see that there will be worn Sagebrush Sparrows migrating northward through canescens territories!

As a note to make things more interesting for us all, the BNA account notes that migrating flocks of "Sage Sparrows" have been found containing both (canescens) Bell's Sparrows and Sagebrush Sparrows.


Hope you find it useful, too!
Jen

Territory Mapping

Vermilion Flycatcher female on nest in screwbean mesquite

I’ve had some folks ask me about territory mapping, so I thought I’d share a bit about how the Nevada Bird Count does it (the Lower Colorado River project does it slightly differently in order to meet their particular program goals – minor variations on the same theme!).   Territory mapping (we’ll often also refer to it as area searching or spot-mapping) is my personal favorite way to get acquainted with birds of a new region or habitat, and is a fantastic way to learn the natural history of bird and plant communities.  Nothing beats point count transects for the chance to hike and explore and get a wide breadth of understanding of your birds and habitat, and their variation across the landscape – but the area searches are a great way to get depth.  Our plots are of variable size – basically, we want a plot to be big enough that we’re able to have it covered by 9:30-ish in the morning, but small enough that we’re able to have it covered well, and aren’t glossing over sections to get them done on time.  Not surprisingly, therefore, our Mojave Scrub plots are going to be a larger size than our coniferous forest or riparian plots – the former have a lot less habitat structure and fewer birds, so we’re able to cover more ground.  A 300 x 300m plot is fairly typical in streamside vegetation, where there’s a lot of structure.  We visit each plot 8-10 times; often our Mojave Scrub or sagebrush plots are able to be thoroughly mapped within 8 visits, but those extra 2 visits can make a big difference in our more complex plots!

Another area search plot, Sandy Valley

Basically, our surveyors are given an aerial photo overlain with a UTM grid, and on each visit, they will walk through the plot in a different pattern, making sure that they get within 50m of every part of the plot on each walk-through.  The different routes ensure that each part of the plot will get surveyed during the best part of the birding morning on at least one occasion, so we don’t have one location that is always surveyed at 5:30 a.m. and one location always surveyed at 9.  We walk through the plot, looking at and listening to birds, watching their behavior, and marking down their locations on our aerial photo.  Once we’ve finished our initial walk-through, somewhere between 9 and 10am, then we’ll often head back to a perplexing area to spend some more time watching, listening, and mapping.   The 2 biggest things to remember are (1) following individuals and (2) simultaneous detections.  When we find an individual, it’s useful to spend some time with it, marking down the path of that individual’s movement, particularly if it’s a singing male or is exhibiting other territorial behavior.   Do we see any behavior indicating where the nest might be found?  Concurrently, you want to look and listen to determine whether you have any other individuals of that species, and if so, map them too.

Here's one of 3 maps that I filled in during a single visit of my area search plot

At the end of the survey, we’ll end up with a map of all of our bird locations, criss-crossed with lines – solid ones indicating the movements of a particular individual, dashed lines indicate that we had different individuals, along with a few scribbled behavioral notes.  The day’s not done yet, though!  We’ll transfer each species’ locations, lines and notes to a species-specific map, that will eventually encompass all of the data for that species from all of the visits.  Before each visit, we’ll scrutinize those maps, and figure out where the territory boundaries are unclear and where we need to spend some more time.  Then, at the end of our 8 to 10 visits, we’ll draw our territory boundaries, and summarize our findings.

If you squint, you can make out letters marking locations: the first visit is A, the 2nd visit, B, and so on.

The area searches are useful for a lot of purposes – they give us detailed natural history information, and because they provide such detailed location information, they’re excellent at monitoring changes in habitat and bird communities through time, so they’re incredibly useful to monitor habitat restoration projects.  Plus we’re able to use them to do some calibrating of our extensive program of point count surveys – by conducting point counts on the area search plots, we’re able to compare what our point count surveyors record to the mapped territories, which helps us determine detection rates.

You don’t need UTM grids and GPS units to do your own territory mapping, though.  Find your favorite park on (for example) google maps, switch to satellite view, zoom in, and print it out.  With a pencil and your binoculars, you’re now set to map out territories of the bird community – or just a species or two of interest.  When you’ve mapped out a territory, take a look at it  - what does it tell you about that species’ habitat/structural needs?  Where is the nest located relative to the territory boundary?  If a pair renests, with either a replacement clutch or a second brood, do their territory boundaries shift?   As they move along in breeding stages, how do their movements change?   Do their defended areas contract, or expand?  And of course, spot mapping doesn’t have to be limited to the breeding season, you can also see how birds’ uses of various habitats changes across the seasons.  All fun things you can explore with mapping! 

Happy birding,

- Jen