Data from: Influence of mate and nest-site fidelity on a declining, urban avian population
Data files
Jun 30, 2025 version files 85.81 KB
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BUOW_Fidelity_Behavior_Data.xlsx
79.50 KB
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README.md
6.31 KB
Abstract
As urbanization reduces species’ habitats and population sizes, managers need information on whether within-population processes, such as changes in mate and nest-site fidelity and dispersal distances, may be contributing to declines. We investigated whether mate fidelity, nest-site fidelity, or breeding dispersal distance changed over time in a population of burrowing owls (Athene cunicularia), a short-lived, socially-monogamous species. During the 18-year period of the study, the population declined by 69% in urban Santa Clara County, California, USA--a region of rapid urbanization. We assessed whether these behaviors were influenced by key factors including age, breeding success in the previous year, and years with the same mate, and examined the relationship between mate and nest-site fidelity over time and annual reproductive success. To evaluate the relationship between mate and nest-site fidelity as well as overall mate and nest-site fidelity rates by sex, we used Chi-Square tests. For all other tests, we used Generalized Linear Mixed Models (GLMM) with individual bird identification as a random variable to address the inclusion of the same birds in multiple years. Our analyses showed no change over time in mate fidelity, nest-site fidelity rates, dispersal distances, or annual reproductive success, indicating these behaviors remained stable even during a severe population decline. Although burrowing owls are a short-lived species, we found that increasing years with the same mate resulted in increased mate fidelity, nest-site fidelity, and annual reproductive success. Since these fidelity behaviors were maintained during the population decline, other factors require investigation to determine the causes for decreases in numbers in this population. Thus, even species such as burrowing owls, which can maintain important fidelity behaviors in urban setting, are still subject to other pressures that can cause population declines.
Dataset DOI: 10.5061/dryad.vt4b8gv3j
Description of the data and file structure
Our objective was to investigate mate and nest-site fidelity rates and breeding dispersal distances in relationship to reproductive success in an avian population declining in an urban setting. Given that urban settings can disrupt mate selection and/or the longevity of nesting sites, we suspected that mate and nest-site fidelity rates might change significantly as the study population decreased. Disruption of these behaviors could then contribute to the declining population through reduced annual reproductive success over time. We analyzed mark-resight data for a population of resident western burrowing owls (Athene cunicularia subspp. hypugaea) over an 18-year period in Santa Clara County, California, an area of rapid urbanization [38].
Files and variables
File: BUOW_Fidelity_Behavior_Data.xlsx
Description: We conducted all statistical analyses using SPSS (v.28; IBM Corporation). The α-level for significance was 0.05. Continuous variables included year, age, dispersal distance, years with the same mate, and annual reproductive success as measured by emergent brood size (number of chicks per brood). Categorical variables were mate fidelity (yes or no), nest-site fidelity (yes or no), breeding success the previous year (yes or no), sex (male or female) and individual bird identification number.
To evaluate the relationship between mate and nest-site fidelity as well as overall mate and nest-site fidelity rates by sex, we used Chi-Square tests. For all other tests, we used Generalized Linear Mixed Models (GLMM) with individual bird identification as a random variable to address the inclusion of the same birds in multiple years. Relationships between mate fidelity or nest-site fidelity and factors that could influence those rates were tested with using a Binary Logistic distribution. The Gamma distribution (log link) was used to compare male to female dispersal distances and for hypotheses testing factors potentially affecting breeding dispersal distances, which was right-skewed, continuous data. Finally, we used the Poisson distribution (log link) to test hypotheses with number of chicks per brood (annual reproductive success), which were count data and to compare the annual reproductive success of birds that did versus did not show mate or nest-site fidelity and compare years with the same mate by sex.
Variables
- year
- age (year)
- dispersal distance (meters)
- years with the same mate
- annual reproductive success (number of chicks per brood)
- mate fidelity (yes or no)
- nest-site fidelity (yes or no)
- breeding success the previous year (yes or no)
- sex (male or female)
- individual bird identification number
Code/software
We conducted all statistical analyses using SPSS (v.28; IBM Corporation). Specific details for analyses using each spreadsheet in the data file are as follows:
- To separate males from females, use the "Sex of Primary Mate" column
- Y=Yes, N=No, S=Successful, F=Failed
- In all GLMM tests, use PrimaryMate_ID (individual bird identification) for the random variable.
- Missing data: Cells will be empty when the outcome was unknown for that year for that variable.
| Spreadsheet Name | Description | Tests with this Data Set |
|---|---|---|
| MateFidelity | Mate Fidelity Records (categorical data: Y or N) | 1) Chi-square for relationship between Mate and Nest-site Fidelity; 2) Chi-square for relationship between Mate Fidelity and Sex; 3) GLMM (Binomial Logistic Regression) with these variables: Year, Age and Breeding success the previous year (select S and F) |
| NestSiteFidelity | Nest Fidelity Records (categorical data: Y or N) | 1) Chi-square for relationship between Nest-site Fidelity and Sex; 2) GLMM (Binomial Logistic Regression) with these variables: Year, Age, Breeding success the previous year (select S and F) and Years with same mate |
| BreedingDispersal | Breeding Dispersal Distance Records (continuous data) | 1) GLMM (Gamma, log link; add 1 to each enty to eliminate 0s) to compare male to female dispersal distances; 2) GLMM (Gamma, log link; add 1 to each enty to eliminate 0s) with these variables: Year, Age, Breeding success the previous year (select S and F) and Years with same mate |
| AnnualReproductiveSuccess | Brood Size Data Records (continuous data) | 1) GLMM (Poisson distribution, log link) to compare birds that did or did not show mate or nest-site fidelity and compare years with the same mate by sex; 2) GLMM (Poisson distribution, log link) with these variables: Year, Age and Years with same mate (remove Years_with_Mate=5; only 2 records) |
| NatalDispersal | Natal Dispersal Distance Records (continuous data) | Natal Dispersal Distance descriptive statistics |
Access information
Other publicly accessible locations of the data:
- None
Data was derived from the following sources:
- No additional sources; data were collected by the study authors