GORILLA MOMS 1 - Behavior Changes

Beginnng in 2004, there was a bit of a baby boom among the gorillas of Colorado.  It began with JoRayK and baby Jabali in Denver, continued in 2005 with Rapunzel and Tinga in Denver, and culminated in 2007 with Asha and Tumani in Colorado Springs.  What a beautiful time, not to mention a great research opportunity!

There had been studies of gorilla infant development and mother-infant interactions, but I wondered - how does life change for the mother?  How does a female gorilla's activity budget change after the birth of her  child - when she begins to spend time tending to her child, she must allocate less time to other behaviors, right?  How do her relationships with other group members change?  Does she hang out in different parts of her environment?

The Exhibits:

The gorilla exhibits at both zoos consisted of large, heavily wooded outdoor areas, in addition to well-furnished indoor enclosures.  The two gorilla groups at Denver Zoo alternated between the outdoor (photo at right) and indoor areas.  At Cheyenne Mountain Zoo the gorilla troop typically had access both indoors and out, weather permitting.

Data Collection:

All data were collected by observing the female for 15 minutes at a time, scoring a behavior every 30 seconds.  I observed each female at the end of her pregnancy, after the baby was born (postpartum), and when the infant was becoming more mobile (7-8.5 months postpartum).

I documented general behaviors, detailed maternal behaviors, proximity to other group members, whether the female was outside or indoors, and if she was in an elevated portion of the exhibit.  It seemed that all of these might change as time passed.

Just by an observer's presence and focused attention, we can and probably do have some effect on the behaviors of the animal being observed, and perhaps on other members of the social group.  Kwisha was pregnant the year before Asha, and silverback Rafiki noticed right away that I was focusing on her.  He kept a close eye on me, and even tried to get a whiff of me where two glass panels joined.  He did come to trust me, and was fine as I observed Asha.

Rapunzel was the only female who appeared overtly affected by my presence.  Due to the crowds of zoo patrons, I had to establish my place next to the exhibit glass so I could see the details of the mothers' behaviors.  Rapunzel sometimes seemed uncomfortable with me hovering over her.  A couple times she hit the glass and grunted or moved away, and I respected her wishes and backed off.  I wondered if this reaction might have been related to her first infant being taken from her (see Gorilla Moms 3).

I observed JoRayK at the end of her pregnancy (photo at right) between April 5 and May 26, 2004, for a total of 7.25 hours (870 data points).  59% of the observations were in the outdoor enclosure and 41% in the indoor exhibit.  Following is Jo's activity budget:

Feeding 39%, locomotion 5%, self-groom 6%, abnormal behaviors (hair pluck) 2%, social .3%, inactive 45%, misc. 2.7%

Most of the self-grooming took place on one day when Jo repeatedly groomed her back.  I was told that earlier there had been a scuffle, ending with Jo and Bassa chasing Jim.  Therefore, I wondered if Jim had injured Jo. 

It was interesting (and very sweet) when later that same day Jim sat behind Jo for six minutes, somewhat gently grooming her back with his fingers and lips, until she moved away to forage.  Of course this happened when I was not collecting data!

The scored social data were composed of one instance when Jo and Angel pig grunted (angry vocalization) at each other, and two scores for Jim displacing Jo.   No affiliative social interactions were recorded.

JoRayK gave birth to her daughter Jabali (photo at right) on May 29, 2004.  I collected 6 hours of data (720 data points) on Jo between June 1 and July 26, 2004.  38% of the observations were outside, 62% in the indoor exhibit.  Here is her activity budget, as well as differences from pregnancy:

Feeding 23% (-16%), locomotion 4% (-1%), self-groom 2% (-4%), abnormal behaviors (pluck, coprophagy, pluck Jabali) 2% (same), social 3% (+2.7%), inactive 47% (+2%), maternal 16%, misc. 3%

Jo's decrease in feeding time was worrisome, especially since lactating females require even more nutrition than pregnant females.  She appeared lethargic and didn't seem to feel well.  She lost weight and keepers had to encourage her to eat.

Jo's coprophagy (eating feces) was associated with diarrhea, which lasted for 1-1/2 months, on and off, and which must have contributed to her lethargy and weight loss. 

 Jo started plucking hair from Jabali almost as soon as she popped out.  It's certainly not unusual for a female who plucks herself to also pluck her offspring, at least until the infant is able to escape.  Jo had plucked hair from her previous offspring.  I even saw Bassa pluck Jabali's head!

The increase in social interactions was both aggressive and affiliative in nature.  Jo was displaced by Jim three times.  I recorded one instance of each of the following:  Jo chased Angel after she attacked Jo; Jo barked at Angel as she and Bassa faced down Angel; Jo and Bassa chased Angel after she displayed past Jo.

Angel seemed to take advantage of Jo, who was now caring for a child, and not feeling well.  Angel performed run-by attacks, especially in the large outdoor enclosure, where she would hit or grab at Jo or Jabali.  Bassa was very good about helping Jo defend herself or chase Angel, and Jim sometimes helped by blocking Angel.  Bassa began adopting a position by Jo and Jabali, appearing to guard them (photo below).

During this time zoo administration introduced a moratorium on "unnatural looking" objects for the gorillas and orangutans, who were housed in the same building.  The male apes seemed to especially miss having fabric for their displays, and Jim increased his aggression against Jo, using her as a display object, dragging her around the exhibit.  Fortunately the keepers were eventually able to provide burlap and brown objects.

Affiliative social interactions included two instances when Jabali was transferred from Jo to Bassa.  As I will discuss in Gorilla Moms 3, Bassa was a wonderful "auntie" for Jabali.  The remaining twelve affiliative scores occurred when Jim approached Jo, groomed her foot, touched her, then groomed her back for 5 minutes (photo below).  Perhaps his grooming was a bit rough, as Jo eventually pig grunted and moved away.

It is striking that Jo's time spent in maternal behavior was exactly the time lost in feeding.  This was the greatest change in Jo's activity budget, but her health status was an extenuating variable.  There was also an increase in social interactions.  The presence of Jabali seemed to attract both Angel and Jim to interact with Jo in different ways. 

The final data set was collected between December 30, 2004, when Jabali was 7 months old, and March 16, 2005.  I observed Jo for 6.75 hours (810 data points), 48% outdoors and 52% inside.  As proximity data will indicate (see Gorilla Moms 2), Jabali was no longer in physical contact with Jo 31% of the time.  Following is Jo's activity budget, as well as differences from postpartum:

Feeding 34% (+11%), locomotion 9% (+5%), self-groom 3% (+1%), abnormal (R&R - regurgitation and reingestion, pluck Jabali) 7% (+5%), social 2% (-1%), inactive 24% (-23%), maternal 19% (+3%), misc. 2%

Jo significantly increased her feeding time and gained weight, indicating she was feeling better.  Her increase in locomotion, together with dramatically decreased inactivity, could have reflected her improved health.  They could also have been related to Jabali's growing independence.  Jabali was no longer in constant contact with her mother, perhaps thereby freeing up Jo.

Jo's abnormal behaviors included 10 scores for R&R and 48 scores for plucking Jabali's hair.

Although social interactions decreased, the patterns were the same.  Aggressive interactions included displaying twice at Angel.  Jo was also displaced by Jim five times.  When I wasn't recording data, Angel displayed past and grabbed at Jo and Jabali.  Jo screamed at Angel, and Jim reacted appropriately by chasing Angel.

Scored affiliative interactions were:  play with Jim - 2; groomed by Jim - 3; retrieve Jabali from Bassa - 2.  The play session with Jim lasted on and off for four minutes.  Jo would walk by Jim with Jabali on her leg and brush against him.  Jim patted Jabali and tried to pick her up, and he would also hold Jo's arm or leg.  She sat in front of Jim and he play bit her shoulder.  On another day Jo offered her back to Jim and he groomed her.

It's interesting that Jo's active maternal behaviors increased slightly, even though Jabali was spending less time in contact with her.  I felt this also had to do with Jo feeling better.

I observed Rapunzel for 4.25 hours (510 data points) at the end of her first pregnancy.  (This infant was pulled for nursery rearing - see Gorilla Moms 3 page for discussion.)  Data were collected between April 5 and May 5, 2004.  59% of observations occurred outside and 41% inside.  Here is Rapunzel's activity budget:

Feeding 22%, locomotion 7%, self-groom 2%, abnormal behaviors (R&R) 18%, social 0%, watch people 2%, inactive 46%, misc. 3%

Evelyn also did a great deal of regurgitation and reingestion of food (R&R), and I wondered if there might be a cultural component.

I recorded no social interactions for Rapunzel, nor did I observe any during breaks in collecting data.

The majority of Rapunzel's people watching occurred while a docent was speaking to the public in front of the gorilla enclosure, so was most likely an anomaly, but enrichment nonetheless.

Rapunzel gave birth to Tinga, her second infant, on May 24, 2005.  Kelly, who had been separated (see Gorilla Moms 3 for explanation), was reunited with the group on June 6, and I gave the group some time to settle down.  I observed Rapunzel between July 8 and August 25, 2005, collecting 6.75 hours of data (810 data points).  During 52% of observations the group was outside and 48% inside.  Following is Rapunzel's activity budget, along with differences from the end of her first pregnancy:

Feeding 21% (-1%), locomotion 5% (-2%), self-groom 3% (+1%), abnormal behaviors (R&R) 5% (-13%), social .2% (+.2%), watch people .4% (-1.6%), maternal 28%, inactive 35% (-11%), misc. 2.4%

Rapunzel's self-grooming increased slightly, I think because she was not experienced at holding Tinga away from her when the infant urinated or defecated.

Rapunzel had a slight increase in social interactions, both of which were affiliative with Kelly.  There was one score when she watched Kelly R&R and one when she smelled Kelly as he walked past her.  So, even though Rapunzel and Kelly were spending more time close to one another (see Gorilla Moms 2), they were not physically interacting.

There was an interesting behavior that I saw in the outside enclosure - on three different days Rapunzel sat and arranged sticks around herself, like a nesting behavior.  I had also seen Evelyn do this, and once again I wondered about a possible cultural component.

The largest changes in Rapunzel's behaviors were decreases in abnormal behaviors (-13%) and idle time (-11%), the total of which approached Rapunzel's time spent in maternal behaviors (28%).

I must mention that Tinga was so tiny, and fingers on her left hand were pink (photo at right), as were the tips of her left toes. Sometimes gorillas are born with pink patches on their hands or feet, which darken over time.  Eleven years later Tinga would give birth to her own daughter, who was also very tiny.

These data were collected between January 22, when Tinga was eight months old, and March 10, 2006.  I observed Rapunzel for 7.25 hours (870 data points), 28% when she was outside and 72% indoors.  Rapunzel's activity budget follows, as well as differences from postpartum:

Feeding 16% (-5%), locomotion 6% (+1%), self-groom 10% (+7%), abnormal behaviors (R&R) 12% (+7%), social .2% (same), watch people 0% (-.4%), maternal 25% (-3%), inactive 30% 

(-5%), misc. .8%

Rapunzel's increase in self-grooming occurred on three separate days when she groomed either her left or right arm.  One day a small wound was visible on her left arm, and another day she was grooming small scabs on her right arm.  I don't know how she received these minor injuries.

The increase in regurgitation and reingestion of food suggests this behavior might reflect boredom.  Rapunzel's R&R decreased significantly postpartum, perhaps because she was occupied with her new infant.  Then it more than doubled six months later.

I only scored two social interactions, one when Evelyn displayed past Rapunzel.  On another day Rapunzel stood by Kelly and stared at him.  About an hour later, when I wasn't recording data (of course!), Kelly was laying on his back, shaking some wood wool.  This seemed to be an invitation to play, as Rapunzel gathered up Tinga, approached Kelly and began to play bite him.  They continued to play bite each other, arms around each other, with Tinga on Rapunzel's back (photos below).

Asha was born on October 5, 1992, at Cheyenne Mountain Zoo in Colorado Springs, to mother Juju and father Barney.  Asha was pulled for hand rearing after two days.  Tumani was Asha's first offspring.

Asha's social group contained three other females - her mother Juju, Roxie, and Kwisha - and silverback Rafiki (photos below).  

I observed Asha between December 13, 2006 and January 19, 2007.  I collected 8.75 hours of data (1110 data points), 5% outside and 95% inside.  Following is Asha's activity budget:

Feeding 24%, locomotion 5%, self-groom 2%, abnormal (R&R) 1%, social 2%, inactive 63%, misc. 3%

All of Asha's scored social interactions were affiliative with Rafiki on one day about a month before Tumani was born.  Rafiki groomed Asha, Asha solicited him for mating, and they mated (photo below).  A keeper told me that a few days before Asha gave birth, Rafiki began to mate with her, but instead put his arms around Asha with his hands on her belly for about 20 seconds before Asha moved away.  I wonder if he felt the baby move.

One of Asha's favorite positions for resting was laying on her belly on an elevated log (photo below).  This became more difficult as her belly got bigger, but she still managed to lay on a log infrequently, positioning her belly to one side.

Keepers did maternal training with Asha, and one day a knotted towel served as her "baby."  She kept that towel with her all day, holding it, carrying it on her back (photos below) or in her "thigh pocket," laying with it on her side.  On days when burlap was available, Asha also kept that with her, resting on it, carrying it on her back, putting it on her head.

During the month before Tumani's birth, twice I observed Asha inspecting her nipples and using her fingers to pull a nipple up and touch it with her tongue.

Tumani was born on January 31, 2007.  The first time I was able to visit them, Asha held Tumani up to the glass in front of my face.  She did this again in April, and I took a photo of the smudge Tumani left on the glass (photo below).   (Asha also presented her second child Dembe to me, in the same way, 5-1/2 years later - three of my most special gorilla moments.)

I collected 6.75 hours of data (810 data points) on Asha between February 10 and March 2, 2007.  During all of these observations, the group was inside.  Here's Asha's activity budget, along with differences from when she was pregnant:

Feeding 19% (-5%), locomotion 3% (-2%), self-groom 2% (same), abnormal (coprophagy) .1% (-.9%), social .5% (-1.5%), maternal 35%, inactive 38% (-25%), misc. 2.4%

Once again, all of Asha's scored social interactions were with Rafiki - he displaced her once, and there were three scores for affiliative interactions.  On one day Rafiki was sitting in front of Asha as she held Tumani.  He reached slowly toward her, she moved toward him, he gathered her up and hugged her briefly until she moved away. 

A few days later, Rafiki was close to Asha, watching Tumani.  He reached out and touched Asha's foot, and she moved toward him, with Tumani.  He had an open mouth play face, and she put her hand on his head.  Later he followed her, put his open play mouth on her back and hugged her.  I continued to observe Asha during the next three  months and saw numerous play sessions between Asha and Rafiki, one of which lasted on and off for 45 minutes (photos below).

Rafiki seemed to entertain himself by pestering one of the females, usually Kwisha, until she screamed and all four females chased him.  When this happened after Tumani was born, the other three females chased Rafiki, but Asha just kept eating.

All of Asha's behaviors decreased in frequency after maternal behaviors (35%) were added.  The largest decrease was in idle time (-25%), and feeding (-5%) and locomotion (-2%) also decreased substantially.

I collected 6.75 hours of data (810 data points) on Asha beginning September 14 and ending November 2, 2007, 42% outside and 58% inside.  Following is her activity budget, as well as differences from postpartum:

Feeding 24% (+5%), locomotion 8% (+5%), self-groom 1% (-1%), abnormal 0% (-.1%), social .4% (-.1%), maternal 5% (-30%), inactive 50% (+12%), not visible 8%, misc. 3.6%

When food had been spread in one part of the enclosure, Rafiki would allow Asha to eat, but would often block the other females from entering that area.

I recorded 3 scores for social interactions:  Rafiki displaced Asha once; Asha took a corn stalk from Kwisha; Asha and Kwisha did a parallel run, after which Kwisha managed to touch Tumani, who was on Asha's back.  Kwisha was very interested in Tumani, often hanging out nearby (photo below) and sneaking a touch.  She was particularly interested in Tumani's "eye boogers." 

Although not captured in the data, I observed play sessions with Rafiki, several in one day.  The first session started when Asha walked past Rafiki, pausing for him to touch Tumani, sitting next to him, and then they played.  A bit later Rafiki initiated play by pulling and play biting Asha's legs as she hung from a ceiling vent.  They continued to play, sometimes initiated by Asha shaking fire hoses or clapping, sometimes initiated by Rafiki (photo below). 

One day Rafiki seemed irritable, and five times he chased, grabbed, or whomped on Juju or Kwisha.  When the females then chased him, Asha did not join them.  After the situations had calmed down, Asha often approached Rafiki with Tumani on  her back (photo below).  It seemed she was calming down Rafiki, or solidifying their relationship.

Rafiki did not approve of his females interacting with people through the glass, and he would charge at the female, prompting the females to scream and chase him.  Asha would just watch.

This phase was frustrating to me as an observer, because Asha took Tumani to areas where I couldn't see them, such as an upper den (photo below).  So I had to utilize a "not visible" category.  If Asha was not visible over half of a 15-minute observation period,  I discarded that entire data set.  Her favorite private place was in a stand of trees at the top of the outdoor enclosure (photo below).  Rafiki would often join them, and I could only imagine the wonderful things the little family was doing up there!  If I could have observed there, Asha's social and maternal behaviors would likely have been greater.

Below are comparisons between the activity budget changes of the three females.   The three columns are for Pregnant, Postpartum, and 7-8.5 Months Postpartum.  I wondered if there would be common changes that therefore could be expected after a female gorilla gives birth.  I also was interested to see if changes might be different for experienced moms and females raising a child for the first time. 

Feeding --

JoRayK:         39%      23%       34%

                                   -16%     +11%

Rapunzel:     22%      21%       16%

                                     -1%        -5%

Asha:             24%      19%       24%

                                     -5%       +5%

All three females spent less time feeding postpartum, which I didn't expect.  This suggests that keepers should not be alarmed if the feeding time of a gorilla mom decreases after she gives birth, unless the decrease is large.  Jo's feeding time decreased much more than the two new moms, but this dramatic change probably reflected Jo's health issues, and keepers did need to compensate for this.

Locomotion --

JoRayK:           5%         4%         9%        

                                     -1%        +5%

Rapunzel:       7%         5%         6%

                                      -2%       +1%

Asha:               5%         3%         8%

                                      -2%       +5%

For all three females, there was less locomotion postpartum, as might be expected, given that they now had a baby on board.  However, a gorilla mom might spend more time moving if she was getting away from other group members, which didn't appear to be the case. Everyone's locomotion then increased a few months later, perhaps because they were carrying the infant less.  Or maybe they were chasing after their exploring toddlers!

Self-grooming --

JoRayK:            6%          2%           3%

                                        -4%        +1%

Rapunzel:        2%          3%         10%

                                       +1%         +7%

Asha:                2%          2%           1%

                                          ----         -1%

There were no clear patterns for self-grooming.

Abnormal --

JoRayK:             2%          2%           7%

                                          ----         +5%

Rapunzel:       18%          5%         12%

                                       -13%         +7%

Asha:                 1%         .1%           0%

                                        -.9%         -.1%

Abnormal behaviors decreased postpartum for the new moms, which suggests their regurgitation and reingestion of food was related to boredom.  Jo's hair plucking increased over time because she plucked Jabali as well as herself.

Social --

JoRayK:            .3%           3%           2%

                                      +2.7%         -1%

Rapunzel:         0%          .2%          .2%

                                        +.2%           ----

Asha:                 2%          .5%          .4%

                                       -1.5%         -.1%   

These data suggest that social interactions might increase postpartum and decrease a few months postpartum.  It seems likely this would be due to the waxing and waning of other group members' interest in the new infant.  Another factor could be that gorilla mothers tend to "introduce" their new infant to the silverback.  They also seem to use the infant as a social buffer, taking advantage of the infant's "protection."  With all three mothers, I had the impression they felt safer interacting with the silverback, knowing he wouldn't take a chance on harming the infant.  Perhaps this was their chance to interact with the silverback in ways they had always wanted.

Inactive --

JoRayK:           45%          47%          24%

                                          +2%         -23%

Rapunzel:       46%          35%          30%

                                         -11%           -5%

Asha:               63%          38%          50%

                                         -25%        +12%

The new moms' idle time decreased postpartum, which I expected.  Jo's inactivity increased, once again probably due to her health.  I was surprised that Jo and Rapunzel's time inactive continued to decrease as their infants matured.  Asha's increase in idle time during the last phase seemed to correlate with her decrease in active maternal behaviors.

Conclusions:  

Two aspects of a female's activity budget can be expected to decrease after she has a baby - feeding and locomotion.  The latter makes sense to me, but a decrease in feeding time seems counterintuitive.  Maybe a mom eats faster when she's occupied with a new baby?  With the exception of Rapunzel's feeding, both of these behaviors then increased over time.

I think we can also expect abnormal behaviors to decrease postpartum.  Jo's stayed the same, probably because she expanded her hair plucking to include Jabali.  Postpartum changes in social behaviors were mixed.  JoRayK, the experienced mom, was the only female with a large increase. As time passed, social interactions of the moms  tended to decrease.

It is not surprising that inactivity would decrease after a female's baby is born.  Jo's slight increase postpartum was related to her health issues.  Asha's increase after Tumani was mobile reflected her more laid back approach to motherhood, which is discussed in Gorilla Moms 3.