Peter S. Coates
Brianne E. Brussee
Roger L. Hothem
Kristy H. Howe
Michael L. Casazza
U.S. Geological Survey
20151203
Night Heron Incubation Data
Tabular Digital Data
http://dx.doi.org/10.5066/F7TT4P1K
Parental incubation behavior largely influences nest survival, a critical demographic process in avian population dynamics, and behaviors vary across species with different life history breeding strategies. Although research has identified nest survival advantages of mixing colonies, behavioral mechanisms that might explain these effects is largely lacking. We examined parental incubation behavior using video-monitoring techniques on Alcatraz Island, California, of black-crowned night-heron Nycticorax nycticorax (hereinafter, night-heron) in a mixed-species colony with California gulls Larus californicus and western gulls L. occidentalis. We first quantified general nesting behaviors, incubation constancy, and nest attendance, and a suite of specific nesting behaviors (i.e. inactivity, vigilance, preening, and nest maintenance) with respect to six different daily time periods. We employed linear mixed effects models to investigate environmental and temporal factors as sources of variation in incubation constancy and nest attendance using 211 nest days across three nesting seasons (2010–2012). We found incubation constancy (percent of time on the eggs) and nest attendance (percent of time at the nest) were lower for nests that were located < 3 m from one or more gull nest, which indirectly supports the predator protection hypothesis, whereby heterospecifics provide protection allowing more time for foraging and other self-maintenance activities. To our knowledge, this is the first empirical evidence of the influence of one nesting species on the incubation behavior of another. We also identified distinct differences between incubation constancy and nest attentiveness, indicating that these biparental incubating species do not share similar energetic constraints as those that are observed for uniparental species. Additionally, we found that variation in incubation behavior was a function of temperature and precipitation, where the strength of these effects was dependent on the time of day. Overall, these findings strengthen our understanding
of incubation behavior and nest ecology of a colonial-nesting species.
The principle objective of this study was to explain variation in incubation behavior of night-herons by investigating effects of heterospecifics, climatic conditions, within-season temporal effects, and other ecological factors.
Study area
Alcatraz Island (37.8°N, 122.4°W) is a 9.1 ha island located in the San Francisco Bay, approximately 1.6 km north of San Francisco, California, and has been managed by the National Park Service since 1973. The island provides important breeding habitat for many avian species within the San Francisco Bay area (Howell and Pollak 1991, Kelly et al. 1993, Saenz et al. 2006). Night-herons were first documented on the island in 1975 (Bradley 2005) and other species that occupy the island include common ravens Corvus corax, western gulls, and California gulls. Historic buildings, roads, remnants of demolished buildings, as well as vegetation such as century plant Agave americana, mirror plant Coprosma repens, rose Rosa spp., fuchsia Fushia spp., English ivy Hedera helix, ice plant Carpobrotus spp., eucalyptus Eucalyptus spp., and cypress Cupressus macrocarpa characterize the island. Breeding season temperatures average from 4–16°C in the beginning of March to 12–20°C in July. The majority of annual precipitation occurs from January to March, ranging from approximately 9 cm in early breeding season (i.e. March) to < 0.5 cm later in the breeding season (i.e. June and July).
Field methods
We conducted intensive island-wide searches on a weekly basis from mid-April through late July of 2010 2012, during which we sought to locate night-heron nests in the early stages of incubation (i.e. < 7 d elapsed from first egg laid). At each nest, we recorded coordinates of all nests using a hand-held Global Positioning System (UTM, North American Datum 1983), as well as the dominant nesting substrate, which consisted of the six categories:
blackberry Rubus spp., fuchsia, English ivy, karo Pittosporum crassifolium, century plant, and rubble piles of demolished buildings (i.e. scrap metal, wood reinforcing rods, and other debris).
We installed video systems on a random sample of night-heron nests stratified by dominant vegetation types. We monitored nests continuously (24-h d–1) using microcameras consisting of seven infrared (950 nm wavelength) light-emitting diodes (30 - 110 mm with a 3.6-mm lens; EZ Spy Cam, Los Angeles, CA) and Digital Video Recorders (DVRs). Cameras were concealed using camouflage duct tape and vegetation, and were installed on sturdy vegetation or on a camouflaged iron stake 0.5– 1.0 m from the selected nest. We used 100 m coaxial cables to connect cameras to 4-channel H.264 DVRs (AV Tech, Hong Kong, China). Each DVR system was camouflaged. Nests with cameras were monitored weekly to confirm nest fates. During the weeks of 7 June and 14 June in 2011, and 7 May in 2012, we recorded precise locations of every California and western gull nest on the island on high-resolution paper topographic maps to investigate the effects of mixed colony nesting on night-heron incubation behavior. Gull nesting data were not collected in 2010 because of timing constraints.
20100415
20120731
ground condition
None planned
-122.425
-122.42
37.828
37.825
None
Black-crowned night herons
incubation behavior
video monitoring
USGS Metadata Identifier
USGS:5661bc26e4b06a3ea36c578e
None
Alcatraz Island
San Francisco Bay
None. Please see 'Distribution Info' for details.
The authors of these data require that users direct any questions pertaining to appropriate use or assistance with understanding limitations and interpretation of the data to the individuals/organization listed in the Point of Contact section.
U.S. Geological Survey, PACIFIC REGION
Peter S Coates
Research Wildlife Biologist
mailing address
800 Business Park Drive
Dixon
CA
95620
530-669-5073
707-678-5039
pcoates@usgs.gov
John M. Eadie, Dept of Wildlife, Fish and Conservation Biology, University of California, Davis, CA, USA.
Environment as of Metadata Creation: Microsoft Windows 7 Version 6.1 (Build 7601) Service Pack 1; Esri ArcGIS 10.2.2 (Build 3552) Service Pack N/A (Build N/A)
No formal attribute accuracy tests were conducted.
No formal logical accuracy tests were conducted.
Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.
A formal accuracy assessment of the horizontal positional information in the data set has not been conducted.
A formal accuracy assessment of the vertical positional information in the data set has either not been conducted, or is not applicable.
Development of the data set by the agency / individuals identified in the 'Originator' element in the Identification Info section of the record.
Unknown
Attribute Table
Table containing attribute information associated with the data set.
Producer defined
NESTID_YEAR
Black-crowned Night-Heron nest ID concatenated with the year the nest was active – used as random effect within the models of incubation behaviors.
Producer defined
Nest ID concatenated with a four digit value representing year
INCCONST
This is the response variable representing percent incubation constancy. To obtain percent incubation constancy, we reviewed video data and quantified specific night-heron incubation behaviors across a random selection of dates, ensuring at least one calendar date of quantified behavioral data for each monitored nest (1 – 10 calendar days per nest). Specifically, we randomly assigned two, 10-minute time intervals per hour to examine diel patterns for each behavior to assure uniform sampling throughout each day. Within the 10-minute intervals, we measured the percent of time (seconds) the bird was engaged in incubation constancy. Incubation constancy was defined as the act of sitting on the eggs with physical contact between the parent and eggs. We assigned each 10-minute interval to one of six daily light periods based on sunrise and sunset data (National Oceanic and Atmospheric Administration. 2013. <http://www.esrl.noaa.gov/gmd/grad/solcalc/sunrise.html>, obtained 30 April 2013). To generate the six periods, we first calculated the amount (min) of daylight as the difference in time from sunrise to sunset and divided this number by three to create three equal daylight periods (early light [EL], mid-light [ML], and late light [LL]). Similarly, we calculated the amount of nighttime to create three equal night periods (early dark [ED], mid-dark [MD], and late dark [LD]). Thus, sunrise marked the change from LD to EL, while sunset marked the change from LL to ED. This accounted for varying length of daylight as the nesting season progressed. The average times that correspond to the onset of EL, ML, LL, ED, MD, and LD were 0600, 1045, 1530, 2015, 2330, and 0245, respectively. For those 10-min intervals that overlapped two light periods, the interval was divided at the cut-time between the two intervals. Data for each bird were averaged across all 10-minute intervals per light period per day. Each row is a unique nest, day, light period combination, the scale at which all statistical analyses were conducted.
Producer defined
0
100
ATTEND
This is the response variable representing percent attendance. Each row is a unique nest-day-light period, the scale at which all statistical analyses were conducted. To obtain percent attendance, we reviewed video data and quantified specific night-heron incubation behaviors across a random selection of dates, ensuring at least one calendar date of quantified behavioral data for each monitored nest (1 – 10 calendar days per nest). Specifically, we randomly assigned two, 10-minute time intervals per hour to examine diel patterns for each behavior to assure uniform sampling throughout each day. Within the 10-minute intervals, we measured the percent of time (seconds) the bird attending the nest. Nest attendance included time spent at the nest site without contact with eggs. We considered a nest attended if the heron was within the field of view of our camera, generally a meter surrounding the nest. We assigned each 10-minute interval to one of six daily light periods based on sunrise and sunset data (National Oceanic and Atmospheric Administration. 2013. <http://www.esrl.noaa.gov/gmd/grad/solcalc/sunrise.html>, obtained 30 April 2013). To generate the six periods, we first calculated the amount (min) of daylight as the difference in time from sunrise to sunset and divided this number by three to create three equal daylight periods (early light [EL], mid-light [ML], and late light [LL]). Similarly, we calculated the amount of nighttime to create three equal night periods (early dark [ED], mid-dark [MD], and late dark [LD]). Thus, sunrise marked the change from LD to EL, while sunset marked the change from LL to ED. This accounted for varying length of daylight as the nesting season progressed. The average times that correspond to the onset of EL, ML, LL, ED, MD, and LD were 0600, 1045, 1530, 2015, 2330, and 0245, respectively. For those 10-min intervals that overlapped two light periods, the interval was divided at the cut-time between the two intervals. Data for each bird were averaged across all 10-minute intervals per light period per day. Each row is a unique nest, day, light period combination, the scale at which all statistical analyses were conducted.
Producer defined
0
100
YR
The year during which the nest was active
Producer defined
2010
2012
LP
Light Period - To generate the six periods, based on sunrise and sunset data (National Oceanic and Atmospheric Administration. 2013. <http://www.esrl.noaa.gov/gmd/grad/solcalc/sunrise.html>, obtained 30 April 2013), we first calculated the amount (min) of daylight as the difference in time from sunrise to sunset and divided this number by three to create three equal daylight periods (early light [EL], mid-light [ML], and late light [LL]). Similarly, we calculated the amount of nighttime to create three equal night periods (early dark [ED], mid-dark [MD], and late dark [LD]). Thus, sunrise marked the change from LD to EL, while sunset marked the change from LL to ED. This accounted for varying length of daylight as the nesting season progressed. The average times that correspond to the onset of EL, ML, LL, ED, MD, and LD were 0600, 1045, 1530, 2015, 2330, and 0245, respectively.
Producer defined
ed
Early Dark
Producer defined
el
Early light
Producer defined
ld
Late dark
Producer defined
ll
Late light
Producer defined
md
mid-dark
Producer defined
ml
mid-light
Producer defined
INIT
Ordinal date of nest initiation for each nest. INIT will vary from nest to nest, but not temporally.
Producer defined
89
173
AGE
For each date of behavior data, this is the number of days since nest initiation for each nest (for a 25-d incubation time). AGE will vary from nest to nest and temporally by day of behavior data.
Producer defined
2
26
ORD
Ordinal date of behavior data (elapse from 1 January). ORD will be the same for all nests with behavior data from the same days, but will vary temporally by day of behavior data.
Producer defined
113
192
ORDSEAS
Number of days since first nest initiation of season. ORDSEAS will be the same for all nests with behavior data from the same days, but will vary temporally by day of behavior data.
Producer defined
31
104
TMIN
This is the minimum temperature (°C) experienced over day of behavior data. Data on temperature and precipitation were obtained from a weather station located in nearby San Francisco, CA (37.7°N, 122.4°W; National Climate Data Center. 2013. https://www.ncdc.noaa.gov/cdo-web/, obtained 30 April 2013). TMIN will be the same for all nests with behavior data from the same days, but will vary temporally by day of behavior data.
Producer defined
8.3
15.6
TMAX
Maximum temperature (°C) experienced over day of behavior data. Data on temperature and precipitation were obtained from a weather station located in nearby San Francisco, CA (37.7°N, 122.4°W; National Climate Data Center. 2013. https://www.ncdc.noaa.gov/cdo-web/, obtained 30 April 2013). TMAX will be the same for all nests with behavior data from the same days, but will vary temporally by day of behavior data.
Producer defined
13.3
27.2
PRCP
Presence or absence of precipitation over day of behavior data. Data on temperature and precipitation were obtained from a weather station located in nearby San Francisco, CA (37.7°N, 122.4°W; National Climate Data Center. 2013. https://www.ncdc.noaa.gov/cdo-web/, obtained 30 April 2013). This will be the same for all nests with behavior data from the same days, but will vary temporally by day of behavior data.
Producer defined
0
1
HAB
This column represents the dominant nesting substrate that nests were located in. These data were collected in the field during weekly nest monitoring visits. HAB will vary from nest to nest, but not temporally.
Producer defined
AGAV
Agave americana
Producer defined
BLCK
Rubus spp.
Producer defined
FUS
Fushia spp
Producer defined
IVY
Hedera helix
Producer defined
KARO
Pittosporum crassifolium
Producer defined
RUBB
i.e., scrap metal, wood, reinforcing rods, and other debris
Producer defined
NESTS
Density of nests per m2 in nesting areas. During weekly field monitoring visits, at each nest, we recorded coordinates using a hand-held Global Positioning System (UTM, North American Datum 1983). In the laboratory, we imported active nest locations for each behavior day to calculate night-heron nest densities established night-heron nesting areas. Spatial analyses were conducted using Spatial Analyst tools in ArcGIS 10.1 (ESRI 2012). NESTS will vary from nest to nest and temporally by day of behavior data.
Producer defined
0.001348693
0.013833306
The entity and attribute information provided here describes the tabular data associated with the data set. Please review the detailed descriptions that are provided (the individual attribute descriptions) for information on the values that appear as fields/table entries of the data set.
The entity and attribute information was generated by the individual and/or agency identified as the originator of the data set. Please review the rest of the metadata record for additional details and information.
U.S. Geological Survey - ScienceBase
Mailing and Physical
Denver Federal Center
Building 810
Denver
CO
80225
1-888-275-8747
sciencebase@usgs.gov
Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
The data is available online at the USGS ScienceBase website; http://dx.doi.org/10.5066/F7TT4P1K
20200827
Brianne E Brussee
U.S. Geological Survey, PACIFIC REGION
Wildlife Biologist
mailing address
800 Business Park Drive
Dixon
CA
95620
530-669-5071
707-678-5039
bbrussee@usgs.gov
FGDC Content Standard for Digital Geospatial Metadata
FGDC-STD-001-1998