Monitoring Avian Productivity and Survivorship (MAPS)

Marshall Canyon Conservation Corridor, La Verne, CA

Report for 2024, with data from 2019-2023 for comparison

This was the sixth and probably the last year of the MAPS program at this location. We had 409 captures, more than in any previous year, and 35 species, more than in any previous year, using the same nets and time periods. We caught two species not previously caught as part of the MAPS program, although they have been caught at this site in other seasons: Yellow-breasted Chat and Common Yellowthroat.

For details on the banding location and the MAPS program, see appendix 2.

Results

In this report, birds are noted by their English common names as published by the American Ornithological Society (AOS) (Chesser et al. 2023). The table above presents the number of captures for 2019 to 2024, in AOS order. Captures includes all birds newly banded, all recaptures (including same day recaptures), and all unbanded birds. Averages for 2019-2023 are given for all species. For species with a previous average of more than 10 captures, shading indicates totals that fall outside of the mean minus or plus one standard deviation.

In 2024, there were 248 newly banded birds, 102 recaptures (1 from 2017, 2 from 2018, 1 from 2019, 4 from 2020, 5 from 2021, 9 from 2022, 29 from 2023, and 48 from this year, and 3 unknown), and 58 birds not banded (primarily hummingbirds and a few birds that escaped).

Discussion

Mist netting is a limited sample method, and many factors contribute to its effectiveness, resulting in random fluctuations in the results. For many species, not enough birds were caught to provide a good basis for any comparison. Of the most commonly caught birds, several had changes greater than one standard deviation from the mean, as shown by the shading in Table 1.

• Anna’s Hummingbird continued its decline. California Thrasher and Spotted Towhee were considerably less than the previous averages.

• Oak Titmouse, Bushtit and Orange-crowned Warbler had considerably more captures than the averages of the previous years.

Websites

Banding results for each MAPS day are posted at https://ebird.org/hotspot/L474328.

Banding is done year-round in Marshall Canyon Conservation Corridor, not only in the MAPS study area but also in the hills next to an southwest of the MAPS area. Results of major banding days are also posted on ebird. The overall totals since 2017 are posted at https://sites.google.com/view/birdbanding/. A report for the 2023 MAPS study is at https://sites.google.com/view/birdbanding/summer-2023-report

ACKNOWLEDGMENTS

Thanks to the City of La Verne for allowing this project in this area.

Thanks to the Pasadena Audubon Society for paying for the mist nets.

Thanks to the volunteers who watched, participated, and helped in 2024: Alexander, Avery, Clara, Elena, Garrett, Jake, Jasmine, Jenna, Jolee, Karina, Krystal, Michelle, and Molly.

LITERATURE CITED

Chesser, R. T., S. M. Billerman, K. J. Burns, C. Cicero, J. L. Dunn, B. E. Hernández-Baños, R. A. Jiménez, A. W. Kratter, N. A. Mason, P. C. Rasmussen, J. V. Remsen, Jr., and K. Winker. 2023. Checklist of North American Birds (online). American Ornithological Society. https://checklist.americanornithology.org/taxa/

DeSante, D.F., K.M. Burton, D.R. Kaschube, P. Velez, D. Froehlich, and S. Albert. 2024. MAPS Manual: 2024 Protocol. The Institute for Bird Populations, Point Reyes Station, CA. https://www.birdpop.org/docs/misc/MAPSManual24.pdf.

Michael Morrison
Federal Bird Banding Permit No. 22030-R

Appendix 1

The MAPS program says that a minimum of five nets should be used, spread out over an eight-hectare area. Due to the constraints of the area in which we are working, we could spread our nets out over only five hectares. I chose to start with eight nets, based on my estimate of an upper limit of what I could handle on my own, but allowing opportunity for volunteers as well. However, I had overestimated my ability to handle nets spread out over such a large area. It took 10-15 minutes just to check the nets, allowing less time to take birds out and process them.

Since the usefulness of MAPS data depends in part on consistency in the amount of effort (number of nets), I kept the number of nets at eight. This means that we often had to band on six days a month instead of three. If we open all eight nets at sunrise, we run the risk of capturing more birds than we can take out of the nets before the next round of net-checking has to begin. Some birds might remain in bags for 2 or more hours before we can process them, preventing adults from taking care of the young. This is not acceptable. The process is sometimes slower because we are also training new volunteers.

Therefore our normal procedure in the past few years has been to open four nets at sunrise, and about three hours later, when we are caught up enough, we can open the additional four nets. I would return one or two days later to make up the missing early-morning hours for the last four nets. In some cases we caught so many birds that we could not open any more nets on the first day, and I had to return on another day for a full six hours. This may not be sustainable for me in future years, so I will probably stop participating in the MAPS program, although I plan to continue banding here at a more manageable pace.

Appendix 2: the MAPS program and the banding site

A year-round bird-banding station was established in 2017 in the Marshall Canyon Conservation Corridor in La Verne, California. Birds were mist netted and banded to monitor the movements of resident and migrant species. In 2019, one part of the area began to be used for the MAPS (Monitoring Avian Productivity and Survivorship) program coordinated by the Institute for Bird Populations (IBP).

As shown on the map below, the banding station is in the Marshall Canyon Conservation Corridor in northern La Verne, CA, about 3 km north of the La Verne Post Office, in hills about 400 meters above sea level.

To make it possible to compare the results of one MAPS station to another, and to compare the results from one year to another, IBP publishes a protocol to be used by all MAPS stations (DeSante et al. 2023). It specifies:

·         The net sites are not to be used in the spring outside of the MAPS program.

·         Nets should be 12-meter, 30-mm mesh, four-tier, black, tethered, nylon mist nets.

·         Each net site is to be used for six hours, starting at sunrise, once during each of the ten, 10-day periods. MAPS period 1 is May 1-10[1]; period 2 is May 11-20; 3 is May 21-30; 4 is May 31-June 9; 5 is June 10-19; 6 is June 20-29; 7 is June 30-July 9; 8 is July 10-19; 9 is July 20-29; and 10 is July 30-August 8.

The Marshall Canyon MAPS station uses eight net sites, and on banding days, nets are checked every 45 minutes.

Conditions in Marshall Canyon Conservation Corridor

The west part of Marshall Canyon Conservation Corridor has riparian habitat dominated by Valley and Coast Live Oaks (Quercus chrysolepis and Q. agrifolia). The banding area is in the drier hills east of and 20-25 meters higher than the creek, which flows year-round in most years.

The riparian area is not suitable for banding because much of the bird activity is in the canopy, the canyon slopes are too steep to permit trails and nets, and there is too much human traffic on the public trail near the creek.

Most of the banding area has not been touched by fire[2] or anthropogenic alteration for at least 50 years. There are old fenceposts and fences 300 meters southwest of the area, and some near its north end; livestock may have been in the study area decades ago. A private road, which has bisected the area since at least 1940,[3] was gravelled in 2019 by the Metropolitan Water District (MWD), but the gates are locked and traffic is minimal.

The north edge of the area may have been disturbed when high-tension powerlines were constructed (before 1940), and again when Live Oak Reservoir was constructed by the MWD in the early 1970s. A pipeline from the reservoir is buried adjacent to the high-tension powerlines. I do not know whether the pipeline was installed by trenching or tunnelling. A housing development east of the banding area (built in the mid-1990s) discharges rain runoff into an intermittent stream on the southeastern edges of the study area.

I have not noticed any substantial changes or trends in the vegetation in the seven years I have been banding in this area. It seems to be at a climax vegetation state.

The area has patches of short (4-5 meter) trees, patches where shrubs are dominant, and patches where grasses are dominant. Trees include California scrub oak (Q. berberidifolia), toyon (Heteromeles arbutifolia), elderberry (Sambucus nigra), and laurel sumac (Malosma laurina). Shrubs include golden currant (Ribes aureum), white sage (Salvia apiana), black sage (S. mellifera), chamise (Adenostoma fasciculatum) and redberry buckthorn (Rhamnus crocea). The dominant grass is foothill needlegrass (Stipa lepida). The habitat may be called chaparral, although some of the trees are taller than what most chaparral has.

The area has a Mediterranean climate. There is occasional frost in winter, and temperatures occasionally reach 40 degrees Celsius in summer. Rainfall at Brackett Field (5 km south-southwest of the banding area) averages about 39 cm each year, 95 percent of it in October to May (World Weather Online 2023).

[1] MAPS period 1 is not used at this location. Figure 3 of DeSante et al., 2023 shows that La Verne is near the boundary of stations that should begin with period 1 and those that should begin with period 2. Danielle Kaschube, IBP’s MAPS coordinator, said that our location should start with period 2 (pers. comm.)

[2] Although I have found charred dead tree trunks 300 meters south of the study area, I have not found any within the study area.

[3] The road is not on the 1928 La Verne topographic map. On the 1940 map it is a dead-end road going 600 meters to the northeast, perhaps to a ranch.