DOI: 10.5061/dryad.np5hqc072
title: Data from: Good guardian, bad parent: tradeoffs between territory defense and parental care in Darwin’s finches

description: Although defending a territory may benefit individuals by allowing them to
 retain important resources, the time and energy costs associated with
 territory defense may lead territory owners to neglect other
 reproductively important behaviors. In this study, we assessed the
 potential trade-off between territory defense and parental care in four
 Darwin’s finch species on Floreana Island, Galápagos. First, using song
 playback, we simulated territory intrusions to measure male aggressiveness
 across multiple stages of the breeding cycle (unpaired, paired,
 incubating, and chick feeding). We conducted 168 playback trials at 98
 nests (37 small ground finch, 28 medium tree finch, 27 small tree finch, 6
 cactus finch). To quantify parental care at each nest, we conducted
 one-hour observations to record the frequency of male food deliveries and
 the duration of female incubation and brooding. We conducted 113 parental
 care observations at 59 nests (24 small ground finch, 18 small tree finch,
 15 medium tree finch, 2 cactus finch). By breeding stage, we conducted 76
 observations at 53 nests during the incubation period (mean ± SE
 observations per nest = 1.43 ± 0.07, range 1–3) and 37 observations at 28
 nests during the chick feeding period (1.32 ± 0.12 observations per nest,
 range 1–3).
description: Study sites and
 species We conducted our study from January to March 2024 on
 Floreana Island in the Galápagos archipelago, at two highland (humid zone)
 sites and one lowland (dry zone) site. The two highland sites, located at
 Asilo de la Paz (1°18’46” S 90°27’16 ”W) and the base of Cerro Pajas
 (1°17’46” S 90°27’06” W), consisted largely of remnant Scalesia
 pedunculata forest. The one lowland (dry zone) site comprised dry
 scrubland dominated by palo santo trees (<em>Bursera
 graveolens</em>) in and around the township of Puerto Velasco Ibarra
 (1°16’28” S 90°29’13” W). Our study included four of the five Darwin’s
 finch species considered extant on the island: the small ground finch
 (<em>Geospiza fuliginosa</em>), common cactus finch
 (<em>Geospiza scandens</em>), small tree finch
 (<em>Camarhynchus parvulus</em>), and medium tree finch
 (<em>Camarhynchus pauper</em>). Small ground finches and small
 tree finches were present at all three sites, medium tree finches only
 breed at the two highland sites, and cactus finches only at the lowland
 site. We did not identify any nests belonging to the island’s fifth extant
 species, the medium ground finch (<em>Geospiza
 fortis</em>). Nest monitoring We
 searched for Darwin’s finch nests at our three study sites and monitored
 the breeding activity of male finches whose territory defense behavior we
 had previously measured. Upon discovering an active display nest, we
 observed the male for ~20 min to determine if he was paired or unpaired.
 We then revisited the nest approximately every three days to confirm the
 male’s current status. If the male became paired, we continued to
 regularly monitor the breeding pair to determine the success of their
 nesting attempt. To establish the breeding stage (incubation or chick
 feeding), we either used a borescope to visually confirm the presence of
 eggs or nestlings or observed the parents’ incubation or provisioning
 behavior with binoculars, following a standardized protocol. When
 observing parental behavior, the observer was seated on the ground,
 approximately 10 m from the nest, with binoculars focused on the nest
 entrance. As Darwin’s finches do not noticeably alter their behavior in
 the presence of a human observer within 5 m, this observer distance was
 unlikely to disrupt parental behavior. All nest observations took place in
 the morning, between 06:00 and 12:00 GALT, to minimize time-of-day
 effects. Territory defense
 trials Our playback stimuli were constructed from Darwin’s finch
 songs recorded on Floreana Island in 2023. We created 25 unique playback
 tracks (8 small ground finch, 8 small tree finch, 7 medium tree finch, 2
 cactus finch), each lasting 3 min (1 min of song playback, 1 min of
 silence, 1 min of song playback). Each 1-minute song playback period
 contained six repetitions of the same male song type, simulating a
 territory intrusion by a single unfamiliar conspecific.
 Upon entering a Darwin’s finch territory, we placed the speaker
 in the branches of a shrub or tree about 5 m from the nest, at a height of
 1–1.5 m. Playback tracks were randomly assigned to each subject, with the
 provision that each male received a conspecific song. We never started
 playback until the male was observed within 20 m of the speaker; in cases
 where the male was unbanded, we waited until he returned to the nest or
 interacted with the female to ensure we were observing the nest owner.
 After playback began, an observer (ACK or SK) narrated the male’s response
 into a digital audio recorder. For each trial, we quantified six response
 variables during the playback period: time (in secs) within 5 m of the
 speaker, time (in secs) within 1 m of the speaker, minimum distance (in m)
 from the speaker, number of flights, number of crosses (flights that
 crossed the speaker), and number of vocalizations (defined in Table 1).
 For a subset of trials (N = 24 of 168 trials), we also recorded the male’s
 behavior during a 1-minute baseline period prior to the beginning of
 playback. Across 168 playback trials, we tested males
 at 98 nests (37 small ground finch, 28 medium tree finch, 27 small tree
 finch, 6 cactus finch). Of these, two small ground finch nests belonged to
 the same color-banded male over two consecutive breeding attempts.
 Territory defense trials were conducted across four stages of the breeding
 cycle: unpaired (male was unpaired and defending a display nest), paired
 (male was paired with a female), incubation (female was incubating eggs),
 and chick feeding (male and female were feeding chicks). Parental care
 observations During incubation and chick feeding, we conducted
 1-hour parental care observations at Darwin’s finch nests between 06:00
 and 12:00 GALT, following long-term standardized protocols for this study
 population. Observers were positioned about 10 m from the nest with
 binoculars focused on the nest entrance. During the incubation stage, we
 recorded: (1) the number of male food deliveries to the incubating female
 at or near the nest entrance, and (2) the total female incubation time
 (mins). During the chick feeding stage, we recorded: (3) number of male
 food deliveries to the chicks or females; and (4) total female brooding
 time (mins). In total, we conducted 113 parental care observations at 59
 nests (24 small ground finch, 18 small tree finch, 15 medium tree finch, 2
 cactus finch). For each observation, we estimated the within-stage timing
 of the breeding attempt based on our timeline of monitoring records. Given
 our monitoring schedule, this estimate was usually considered precise to
 within 3 days. Using this estimate, we then broadly assigned each protocol
 to the early (day 1–7) or late (day 8–14) stage of incubation or chick
 feeding.
description: # Good guardian, bad parent: tradeoffs between territory defense and
 parental care in Darwin’s finches Andrew C. Katsis^1,2*^, Lauren K.
 Common^1,2^, Çağlar Akçay^3^, Sonia Kleindorfer^1,2,4^ 1. Konrad Lorenz
 Research Center for Behavior and Cognition, University of Vienna, Grünau
 im Almtal, Austria 2. Department of Behavioral and Cognitive Biology,
 University of Vienna, Vienna, Austria 3. School of Life Sciences, Anglia
 Ruskin University, Cambridge, United Kingdom 4. College of Science and
 Engineering, Flinders University, Adelaide, South Australia, Australia
 *Corresponding author:
 [andrewckatsis@gmail.com](mailto:andrewckatsis@gmail.com) ####
 **Description of the data and file structure** *Full details for this
 dataset are given in Katsis et al. (2025,*Behavioral Ecology*). ####
 **Files and variables** ***File: TerritoryDefense.csv***
 **Description:** This file contains the behavioral responses of male
 Darwin's finches to simulated territory intrusions. Playback trials
 were conducted in February and March 2024 on Floreana Island. Statistical
 methods are described in the associated paper by Katsis et al. (2025,
 Behavioral Ecology). **Variables** *TrialID:* Unique ID for a single
 playback trial (combination of nestID and date)\ *NestID:* Unique ID for
 each nest; nests that are taken over receive a new nestID\ *NestID_Stage:*
 Combination of nest ID and the breeding stage during which the trial took
 place\ *MaleID_Alu:* Unique ID for each male nest owner. If banded, the
 male's aluminium band number is listed; otherwise, the nestID is
 substituted.\ *Site:* Site at which the nest was located. Cerro Pajas and
 Asilo de la Paz are both sites in the humid highlands.\ *Date:* Date on
 which the trial was conducted (YYYY-MM-DD)\ *Observer:* Experimenter who
 conducted the playback trial (ACK = Andrew C. Katsis, SK = Sonia
 Kleindorfer)\ *Time:* Time when the playback trial was conducted (24-hour
 time, Galápagos time)\ *Species:* Species of male nest owner (SGF = small
 ground finch, CF = cactus finch, STF = small tree finch, MTF = medium tree
 finch)\ *PlaybackTrack:* Unique ID for the playback track used for the
 trial\ *TrialNo:* The nth trial conducted for this male (range 1-6),
 regardless of breeding stage or nestID\ *TrialNo_Nest:* The nth trial
 conducted for this nest (range 1-6), regardless of breeding stage\
 *BreedingStage:* The breeding stage during which the trial was conducted
 (unpaired male, paired male, incubation, chick feeding)\ \
 *Baseline_TimeWithin5m:* Baseline period: Time (secs) spent within 5 m of
 the speaker\ *Baseline_TimeWithin1m:* Baseline period: Time (secs) spent
 within 1 m of the speaker\ *Baseline_MinDistance:* Baseline period:
 Minimum distance (m) from the speaker\ *Baseline_Flights:* Baseline
 period: Number of flights\ *Baseline_Crosses:* Baseline period: Number of
 crosses over the speaker\ *Baseline_Songs:* Baseline period: Number of
 trill songs produced\ *Baseline_Whistles:* Baseline period: Number of
 whistles produced\ *Baseline_Buzzes:* Baseline period: Number of buzzes
 produced (tree finches only) (Note: "na" in the above columns
 indicates that baseline behavioral data were not recorded prior to the
 playback trial.)\ \ *Min1_TimeWithin5m:* Minute 1: Time (secs) spent
 within 5 m of the speaker\ *Min1_TimeWithin1m:* Minute 1: Time (secs)
 spent within 1 m of the speaker\ *Min1_MinDistance:* Minute 1: Minimum
 distance (m) from the speaker\ *Min1_Flights:* Minute 1: Number of
 flights\ *Min1_Crosses:* Minute 1: Number of crosses over the speaker\
 *Min1_Songs:* Minute 1: Number of trill songs produced\ *Min1_Whistles:*
 Minute 1: Number of whistles produced\ *Min1_Buzzes:* Minute 1: Number of
 buzzes produced (tree finches only)\ \ *Min2_TimeWithin5m:* Minute 2: Time
 (secs) spent within 5 m of the speaker\ *Min2_TimeWithin1m:* Minute 2:
 Time (secs) spent within 1 m of the speaker\ *Min2_MinDistance:* Minute 2:
 Minimum distance (m) from the speaker\ *Min2_Flights:* Minute 2: Number of
 flights\ *Min2_Crosses:* Minute 2: Number of crosses over the speaker\
 *Min2_Songs:* Minute 2: Number of trill songs produced\ *Min2_Whistles:*
 Minute 2: Number of whistles produced\ *Min2_Buzzes:* Minute 2: Number of
 buzzes produced (tree finches only)\ \ *Min3_TimeWithin5m:* Minute 3: Time
 (secs) spent within 5 m of the speaker\ *Min3_TimeWithin1m:* Minute 3:
 Time (secs) spent within 1 m of the speaker\ *Min3_MinDistance:* Minute 3:
 Minimum distance (m) from the speaker\ *Min3_Flights:* Minute 3: Number of
 flights\ *Min3_Crosses:* Minute 3: Number of crosses over the speaker\
 *Min3_Songs:* Minute 3: Number of trill songs produced\ *Min3_Whistles:*
 Minute 3: Number of whistles produced\ *Min3_Buzzes:* Minute 3: Number of
 buzzes produced (tree finches only)\ \ *HatchingSuccess:* (for trials
 conducted during the incubation stage) whether the nest hatched at least
 one offspring. Y = at least one offspring hatched, N = no offspring
 hatched, uk = hatching success unknown due to inadequate monitoring, na =
 not applicable, indicating that hatching success is not a relevant metric
 for this nest, either because eggs were not laid or because chicks were
 already hatched when experiments began. ***File: ParentalCare.csv***
 **Description:** This file contains parental care data from nest
 observations of Darwin's finches. Data were collected from January to
 March 2024 on Floreana Island. Statistical methods are described in the
 associated paper by Katsis et al. (2025, Behavioral Ecology).
 *ObservationID:* Unique ID for a single one-hour nest observation
 (combination of nestID and date)\ *NestID:* Unique ID for each nest; nests
 that are taken over receive a new nestID\ *NestID_Stage:* Combination of
 nest ID and the breeding stage during which the trial took place\ *Site:*
 Site at which the nest was located. Cerro Pajas and Asilo de la Paz are
 both sites in the humid highlands.\ *Date:* Date on which the observation
 was conducted (YYYY-MM-DD)\ *Time:* Time when the observation was
 conducted (24-hour time, Galapagos time)\ \ *Observation:* The nth trial
 conducted for this nest at each breeding stage\ *BreedingStage:* The
 breeding stage during which the trial was conducted (incubation or chick
 feeding)\ *WithinStage:* Estimated within-stage timing of the breeding
 attempt (early = day 1–7 of incubation or chick feeding, late = day 8–14
 of incubation or chick feeding)\ *Observer:* Observer/s who conducted the
 nest observation (AB = Abbie Hay, ACK = Andrew C. Katsis, AH = Alena Hohl,
 CL = Calean Linke, JD = Jeff Dawson, JK = Johanna Kniely, KA = Katherine
 Albán Morales, LH = Leon Hohl, LKC = Lauren K. Common, MK = Melanie
 Kaluppa, MM = Matt Milham, RD = Rachael Dudaniec, SK = Sonia Kleindorfer,
 US = Ursula Scuderi)\ *MaleSpecies:* Species of male nest owner (SGF =
 small ground finch, CF = cactus finch, STF = small tree finch, MTF =
 medium tree finch). Note that the female nest owner is usually but not
 necessarily conspecific.\ *MaleID_Alu:* Unique ID for each male nest
 owner. If banded, the male's aluminium band number is listed;
 otherwise, the nestID is substituted.\ \ *Brood_Inc_Duration:* The total
 duration (in mins) of incubation or brooding across the 60-min
 observation\ *MaleFeedsFemale:* The number of food deliveries by the male
 to the female, either during the incubation or chick feeding stage\
 *MaleFeedsChicks:* The number of food deliveries by the male to the
 chicks, during the chick feeding stage\ *FemaleFeedsChicks:* The number of
 food deliveries by the female to the chicks, during the chick feeding
 stage ***File: SupplementaryDataFile.xlsx*** This file contains the same
 data outlined above in "TerritoryDefense.csv" and
 "ParentalCare.csv", but in an Excel spreadsheet. The file
 includes two sheets containing data ("TerritoryDefense" and
 "ParentalCare") and one sheet containing definitions of every
 variable ("Key"). ***File: SupplementaryRCode.txt*** This file
 contains the R code used to prepare and analyse the data used in this
 study. ***File: SupplementaryROutput.html*** This file contains the R code
 used to prepare and analyse the data used in this study, in addition to
 the output from each analysis (including statistical outputs and figures).
 This file is formatted using R Markdown. ***File: PlaybackTracks.zip***
 This ZIP file includes all 25 playback tracks (as WAVE files) that were
 used to conduct our territory defence trials. Each track lasts 3 mins (1
 min of song playback, 1 min of silence, 1 min of song playback) and all
 songs within a track are from the same male individual. Each 1-min song
 playback period contains six repetitions of the same male song type,
 simulating a territory intrusion by a single unfamiliar conspecific. We
 used a high-pass filter to remove sounds &lt; 1 kHz and saved the playback
 tracks as uncompressed 16-bit WAVE files. Of the 25 playback tracks, N = 8
 feature small tree finch song, N = 8 small ground finch song, N = 7 medium
 tree finch song, and N = 2 common cactus finch song. **Playback tracks:**
 \* *CF_Track01.wav*\ \* *CF_Track02.wav*\ \* *MTF_Track01.wav*\ \*
 *MTF_Track02.wav*\ \* *MTF_Track03.wav*\ \* *MTF_Track04.wav*\ \*
 *MTF_Track05.wav*\ \* *MTF_Track06.wav*\ \* *MTF_Track08.wav*\ \*
 *SGF_Track01.wav*\ \* *SGF_Track02.wav*\ \* *SGF_Track03.wav*\ \*
 *SGF_Track04.wav*\ \* *SGF_Track05.wav*\ \* *SGF_Track06.wav*\ \*
 *SGF_Track07.wav*\ \* *SGF_Track08.wav*\ \* *STF_Track01.wav*\ \*
 *STF_Track02.wav*\ \* *STF_Track03.wav*\ \* *STF_Track04.wav*\ \*
 *STF_Track05.wav*\ \* *STF_Track06.wav*\ \* *STF_Track07.wav*\ \*
 *STF_Track08.wav* This ZIP file also includes
 "*PlaybackTracksDetails.csv*", a summary of each playback track
 and the individuals whose songs were used to construct them. The variables
 in this spreadsheet are defined below: *PlaybackTrack:* Unique ID for each
 playback track that was used in our territory defense experiment\
 *Recorder:* The experimenter who recorded the Darwin's finch song
 (Çağlar Akçay, Alper Yelimlieş, or Sonia Kleindorfer)\ *Date:* The date on
 which the songs were recorded\ Species: The Darwin's finch species
 that features in the recording\ *ScientificName:* The scientific name of
 the Darwin's finch species that features in the recording\ *Sex:* The
 sex of the individual featured in this recording (always male in this
 dataset, as only male Darwin's finches sing)\ *Age:* The life stage
 of the individual featured in this recording (adult, juvenile, or
 unknown). Adults are 1+ years old.\ *PlumageColour:* The plumage colour of
 the individual featured in this recording, ranging from B0 (approximately
 1 year old) to B5 (approximately 6+ years old). Male body color (in ground
 finches) or head color (in tree finches) darkens during their first six
 years.\ *GeographicalArea:* All recordings took place in the Galápagos
 Islands.\ *Island:* All recordings took place on Floreana Island.\ *Site:*
 The site where the individual was recorded. "Lowlands" is the
 lowland area in and around the township of Puerto Velasco Ibarra.
 "Cerro Pajas", "Asilo de la Paz", "Asilo
 Track", and "Post Office Bay Trail" are all located in the
 highlands.\ *RecordingGear:* The recorder used to create this recording
 (Marantz PMD 660 or Zoom H5)\ *Microphone:* The microphone used to create
 this recording (Sennheiser ME67/K6 or Sennheiser MKE600) #### Version
 changes **2025-09-22:** Added ZIP file "*PlaybackTracks.zip*",
 which contains all 25 playback tracks (as WAVE files) that were used to
 conduct our territory defence trials. This ZIP file also contains a
 spreadsheet summary of each playback track and the individuals whose songs
 were used to construct them.